quality marks – Symbols stamped on articles made of precious metals, prescribed by law or by regulations of government bureaus, to inform and protect purchasers as to the quality of metals in goods offered for sale. The quality of gold is indicated by karat-figures. Pure gold would be stamped 24 karat; gold alloy containing 18 parts by weight of pure gold and 6 parts of other metals is “18 karat gold,” abbreviated “18k,” etc. The karat-figure is always the number of 24ths by weight of pure gold in the total weight of the article. A piece stamped “12k” would have 12/24 its weight of pure gold, and the other half of other metal. Silver marked “Sterling” is .925 pure silver, and .075 other metal. Silver marked “Coin” is .900 pure silver, and .100 other metal. Platinum must be .985 pure to be stamped “Platinum,” or “Plat;” if alloyed with other metals of the platinum group, the piece must be marked showing the proportion of such metal, for example: “Platinum .900— Iridium, .100.” See also KARAT; TOLERANCE; NATIONAL STAMPING ACT; STERLING; PLATINUM; E. P. N. S.; GOLD-FILLED; HALL-MARKS; ROLLED GOLD PLATE.
quartation – In assaying and refining, the addition of silver to a gold bead or button in such quantity as to reduce the gold content to approximately 25 per cent, or one-quarter of the whole. When the resulting alloy is “parted” with nitric acid, the impurities, together with the silver, will be dissolved. Same as inquartation.
quarter nut – A regulating device on precision watches and chronometers, a pair of nuts turning on fixed screws projecting beyond the balance rim, in same positions as quarter-screws; the nuts are turned by a wrench like a screw-driver with a slot cut through the center of its blade. See QUARTER SCREWS.
quarter screws – Timing screws, each set at a point in the circumference of a watch balance rim, 90 degrees from ends of balance arms; for regulating timekeeping.
quarter snail – In a striking or repeater watch, the four-step cam on center post that governs the fall of the rack that determines the number of quarter-hours to be struck when the push-piece is operated.
quartz – Silicon dioxide, one of the commonest of all minerals. It crystallizes in the hexagonal system; has a refractive index of about 1.55; sp. gr. 2.7; hardness, 7. It is colorless when pure, but is commonly colored by many impurities, so that it can be found in almost any hue. It crystallizes in large crystals or may form compact masses of tiny crystals; and it may be perfectly transparent or translucent to almost opaque. With its various classes it forms one of the principal gemstones, but because of its abundance, it never attains first rank in value. For further details, see such listings as AGATE; AMETHYST; CHALCEDONY; CITRINE; JASPER; FLINT; CHERT; ROCK CRYSTAL; ROSE QUARTZ; BLOODSTONE; CHRYSOPRASE; ONYX; CARNELIAN; PRASE; PLASMA; TIGER EYE, etc.
quartz cat’s-eye – A variety of quartz which has many parallel needles of included hornblende. It is white, light to dark leek or gray-green; when cut cabochon it shows an eye, like a true cat’s-eye. It is found in Ceylon with true-cat’s-eye, and in numerous other localities.
quartz crystal – Horol. A material that occurs naturally but can also be commercially synthesized, used in “quartz analog” and solid-state watches. When activated by electrical impulses, a quartz crystal vibrates at very high and very stable frequencies. Oscillation rate depends on shape. In most solid-state watches, the crystal vibrates at 32,768 Hz. (cycles per second), which is evenly halved by an integrated circuit down to 1 cycle per second.
quartz timepiece – A term for two groups of electronic timepieces that have only a quartz time-base in common. 1. The electromechanical group has balances, wheels, tuning forks, vibrating reeds and tiny stepping-motors. Its time presentation is of the analog type, because the dial, hands and numbers or markers are analogous, or comparable, to a 12-hour time-span. 2. The solid-state group has no hands or moving parts. Its time presentation is by digital display, a numerical readout on a rectangular screen. See LIGHT-EMITTING DIODE; LIQUID CRYSTAL.
quartz topaz – A misleading term for citrine.
quartzoid – A crystal shape characteristic of quartz which has crystallized at high temperature, unlike common quartz. It consists of two hexagonal pyramids, base to base.
quatre-couleurs – Kind of decoration on gold goods, a design roughed out in pieces of gold of various colors soldered on plain gold background, these then engraved or chased into final form and finish.
Quebec diamond – Misnomer for quartz crystals.
Queensland opal – Opal with a characteristic light yellowish ground color, found over a large area in Queensland.
Queensland shell – See MACASSAR SHELL.
queen’s metal – An alloy of tin, antimony, bismuth and lead, has lower melting point than Britannia metal, but used for about the same purposes, and for applied cast ornamental features on harder metals.
queen shell – Shell of a conch used in cameos.
queenstownite – See MOLDAVITE. This is a variety of silica glass found in the Jukes-Darwin mining field near Queenstown in western Tasmania. It is richer in silica than most tektites and is white, to green to black. Its sp. gr. varies between 1.85 and 2.30. The pieces vary from tiny drops and fragments, up to 2-1/2 inches in length, and generally contain small bubbles.
queluzita – Brazilian term for spessartite.
quenching – The sudden cooling of hot metal that results in its hardening. See HARDENING; STEEL.
queue, en – Referring to the type of train in a timepiece in which the wheels are arranged in a straight line.
quicksilver – The older term for the element mercury.
quick train – Watch train with gears calculated to produce more than 18,000 beats of the balance per hour, which gradually replaced the slower 16,200 beat train of English and earlier American watches, hence the term “quick” train. See GEARING; ODD-BEAT.
quill – A tubular holder for a tool or shaft; example, the type of sliderest tool holder for watchmaker’s lathe, that holds round-shanked instead of square cutting tools.
quincite – Erroneously spelled quinzite, this crept into gem nomenclature through error. It is applied to a pink sepiolite (magnesite in French) found in Quincy-sur-Mer, in the Loire Basin. Sepiolite is a soft, hydrous magnesium silicate. However, associated with this material there is an attractive, rose-colored common opal, to which the name has erroneously been applied in some gem books. The color is supposed to be of organic origin, and is destroyed by very little heating.
rack – 1. Toothed segment turning on a pivoted arm and working in connection with a snail, to control the number of strokes on bells or gongs of striking watches or clocks. 2. Any toothed segments, straight or curved, working with a wheel or pinion. See SNAIL.
rack-and-pinion – Form of gearing in gravity-wound clocks in which a toothed wheel engages a toothed bar, transforming rotary motion into linear motion, or vice versa.
rack hook – The detent engaging the rack in a striking clock that prevents its tail falling back upon the snail after a rack tooth has been gathered up by the counting or gathering pallet.
rack striking – Striking mechanism in timepieces in which the number of strokes is counted by the number of rack teeth gathered up by a counting pallet, & the fall of the rack.
rack tail – The extension on a rack of a striking mechanism that contacts the snail and limits its drop.
radial pitch – In calculating gearing, a measure equal to the pitch radius of a wheel or pinion divided by its number of teeth. See GEARING.
radient – Synthetic white spinel.
radio opal – Smoky brown common opal colored by organic impurities.
radium hands – Skeletonized hands for watches and clocks, with spaces for holding luminous enamel.
radium treatment – The earliest of the diamond coloration treatments, involving the risky business of dipping a stone in radium bromide. The method produced a skin-deep green, but left a radioactive skin on the stone that was risky to both the operator and the subsequent buyer. Radium-treated stones, which date from about 1912, are still radioactive. Only strong heating or repolishing will remove the radioactivity as it removes the color.
radiumite – Name applied to cabochon cutting material consisting of black urananite or pitch blende (the principal ore of radium) and its decomposition products, orange gumite, brown clarkeite and yellow uranotile. Found in several localities in the United States, it has been cut by amateur lapidaries.
railroad hands – Style of hands commonly used on railroad watches, their unadorned appearance permitting greatest accuracy in telling the precise time.
railroad watch – A watch of a model and grade specified by rules of the time-inspection service of a railroad, and required to be used by all employees having to do with the operation of trains. Specifications vary on different railroads, but in general they call for a watch with a maximum error of 30 seconds a week. Prior to the Nineteen Fifties, the railroad watch was a pocket watch not smaller than 16 size, open face, lever set, full jeweled, adjusted to 5 positions, heat, cold, and isochronism.
rainbow agate or chalcedony – Thin slices of a variety of agate which show prismatic colors along some of its layers by transmitted light. See IRIS AGATE.
rain stone – Quartz in waterworn pebbles.
ratchet – 1. A wheel, with teeth in which a click or pawl engages to prevent backward motion; or the same with addition of another click through which power is imparted at intervals to move the wheel. 2. The combination of a wheel with a click or pawl. See CLICK; RECOILING CLICK; PAWL.
ratchet cap – Steel plate screwed to the bridge in a watch or clock to hold the ratchet wheel in place.
rate – A numerical statement of the error of a timekeeper, its gain or loss per day. Though no instrument keeps perfect time, a precision timepiece may have a constant daily rate, which multiplied by the number of days since the hands were last set yields the correction; i.e., the number of seconds or fractions of a second by which the timepiece is faster or slower than correct time.
rating nut – The regulator nut on screw at bottom of pendulum rod, or on some quarter-screws in watches. See QUARTER NUT.
rat-tail file – A tapered round file of small size with fine-cut teeth.
raying – A line-finish on steel winding wheels, in curved lines radiating from the center. See LINE-FINISH.
Rayner refractometer – A small pocket size instrument (see REFRACTOMETER) characterized by a fixed prism rather than a rotatable hemisphere. (See TULLY REFRACTOMETER).
reamer – A cutting tool for enlarging, truing, or otherwise altering the form of a hole. In horology and jewelry work, the type of reamer most used is the broach, for enlarging or polishing drilled holes. See BROACH.
rebanking – A fault in action of lever escapement, usually caused by a too-strong mainspring, in which excess of balance motion carries the roller jewel too far until it strikes and rebounds from the outside of a forkhorn, instead of stopping and reversing its motion by tension of the hairspring. The rebounds cause erratic speeds of balance motion, hence erratic timekeeping. See OVERBANKING.
rebush – To replace the worn bearing holes in clocks with bushings.
receiving pallet – The entrance pallet of an escapement.
recessing – Turning flat-bottomed depressions in watch plates, etc., to accommodate wheels or other acting parts.
recoiled (or recoiling) mainspring – Mainspring with a reverse-curve on its outer coil, intended to increase the resilient power of the spring. See RESILIENCE.
recoiling click – In stem-winding watches, a click, engaging with the ratchet wheel, that has an elongated hole for its holding screw, or other means for allowing the click and ratchet to move backward a little, after mainspring is fully wound, to avoid straining the spring or its fastenings.
recoil escapements – Class of escapements in which, after locking has occurred, the pallet forces the escape wheel backward a little, before the forward movement of the wheel is resumed. All other escapements are classed as dead-beat, having no recoil. See DEAD-BEAT.
recorder – Horology. 1. A clock with auxiliary mechanism for stamping a record of the time when persons enter or leave their place of employment. 2. An instrument that stamps a record of the timekeeping rates of watches, during regulation or adjustment. 3. An extra dial with hand showing elapsed time as a feature of a chronograph watch.
rectifier – A device that changes alternating current to direct current.
red gold – Gold alloyed with copper, the proportion of copper varying between 25 per cent and 50 per cent, the latter producing the darkest red.
Red Sea pearls – Coral beads, a bad misnomer since true pearls formerly were found there in some abundance and some are still found.
red schorl – Rutile.
red-top moss agate – A variety of Montana moss agate which has a red iron oxide stain at the base of the black dendrites.
reducing gearing – A train of wheels and pinions in which pinions turn wheels, resulting in each successive mobile running slower than its driver, an example being the dial-train of a timepiece; differentiated from “multiplying gearing.” See DRIVEN; DRIVER; GEARING.
reference disc – A block of hard steel ground to exact dimensions; used as a standard for periodical comparison and correction of gauges that are subject to wear in use.
refining – In metallurgy, operations performed to extract metals in purer form from masses containing other metals or impurities.
reflecting loupe – Watchmakers’ magnifier with pierced concave mirror for projecting light inside of watch movement.
reflection goniometer – See GONIOMETER. This instrument measures angles of reflection of a beam of light, and the angles between faces or facets are determined in this way. A contact goniometer is arranged so that two edges are parallel to the two facets and the angle read from a protractor; it is a less accurate method.
reflectivity meter – An instrument for measuring the reflectivity of gem surfaces in relation to refractive indices; it directs energy perpendicularly upon a surface and records the amount of energy returning immediately from that surface. Among such meters are Gemeter, Jeweler’s Eye and Re-dex.
reflector – 1. The polished, beveled ring under the crystal edge of a wrist watch. 2. A diamond with one or more inclusions that reflect to multiply their apparent number.
refraction – The deflection from a straight path suffered by a beam of light when that part of it which is not reflected back into the first medium enters another medium. If the latter medium is of greater density, as with a gem-stone, the light is slowed and bent towards the “normal” (i.e., aline perpendicular to the surface at point of entry). If the medium is of lesser density, as when a ray emerges from a stone into air, the light is speeded, and bent away from the normal. See DOUBLE REFRACTION.
refractive index – A measure of the amount by which light is bent as it passes from air into a transmitting substance such as a gemstone. It is a ratio derived from the sine of the angle of incidence divided by the sine of the angle of refraction. Sodium light, nearly monochromatic with a mean wavelength of 5893A, is used to measure the refractive index of a substance. The refractive index varies from the 2.42 of diamond or even higher figures for metallic substances such as hematite down to 1.45 or even less for opal. Strong refraction is essential to a truly brilliant stone. Faceters vary the angle of the facets depending upon the strength of each mineral’s refraction. The less intense the refraction, the deeper they must cut the stone, if a modicum of incident light is to be bounced back through its face. Lower-index stones cut with enough depth to create moderate brilliance must stand uncomfortably high on the finger, while a high-index stone like diamond need not be ungainly when cut for maximum reflection.
refractometer – (re’frac-tom”met-er). An instrument for measuring the index or indices of refraction of a substance; used in stone identification. There are many types of instruments, some are for liquids and some have been especially designed for gem stones.
Registered Jeweler – A title awarded by the American Gem Society to retail jewelers who satisfactorily complete both a course of study and proctored examinations.
regulating – Making the mean or average timekeeping rate of a watch faster or slower, by moving the regulator or adding weight or subtracting it from the balance; differentiated from “adjusting” a watch, which comprises altering its rates while running in the different positions or temperatures, to make them uniform under varying conditions. In pendulum clocks, regulating is done by raising the bob which shortens the pendulum, to obtain a faster rate, or vice-versa for a slower rate. See ADJUSTING; MEANTIME; RATE; REGULATOR.
regulating dial – A dialette whose hand may be moved to regulate the pendulum or balance’s speed.
regulating stand – Adjustable frame for holding clock movements outside of their cases for greater accessibility during testing after repairing.
regulator – 1. An accurate clock used for comparison of time in setting or regulating other timepieces. 2. A device holding the hairspring curb-pins in a watch, by which they may be moved to various concentric positions on the overcoil of the spring, having the effect of lengthening the spring to make the watch run slower, or shortening it to make the watch run faster. The amount of movement of a regulator is indicated by a pointer against a graduated arc on the balance bridge of plate of the watch. See CURB-PINS.
regulator spring – U-shaped spring of tempered steel, with screw for micrometric adjustment of watch regulator.
rejection cleavage – The third classification grade of diamonds at the mines, they contain numerous inclusions and must be cleaved for cutting. Said to have been the lowest of the four grades commonly used for rough classification before 1890.
relay, circuit – A device which, upon opening or closing, affects another circuit.
relief – 1. The character of carved or engraved work; the height of its features above or their depth below the surface of the background, as high relief, low relief, or hollow relief. See CAMEO; INTAGLIO. 2. Angle ground off the front of a cutting-tool, to avoid contact there against the work, to give the cutting edge free action. 3. The extent to which an inclusion in a gem material stands out against its background.
reluctance – The resistance to a magnetic circuit.
remanance – Magnetism remaining after the initial magnetic influence is removed.
remontoir – 1. Pertaining to winding, as “pignon remontoir”—winding pinion. 2. A stem-wind watch, as in U.S.A.; or a keyless watch, as in England. See REMONTOIRE.
remontoire – Device in train of a timepiece, in which the main motive power winds at short intervals a subsidiary mainspring in the train near the escapement, intended to equalize the power delivered to the escapement.
repair-clamp – A tool used by jewelers, adjustable for holding the parts of a job against each other while being soldered.
repeater – A watch or a clock that strikes the time on gongs whenever a fingerpiece outside the case is operated. See MINUTE REPEATER; TEN-MINUTE REPEATER; QUARTER-REPEATER.
repeater slide – In a watch, the slide piece on the case edge that activates the repeating mechanism.
repivoting – An operation for replacing a broken pivot without discarding the staff or pinion to be repaired. The broken pivot stump is stoned off; a V-center turned in the flattened area; a hole, larger than the former pivot, is drilled with a flat drill, and into it a slightly tapered tempered steel pin is driven tightly. On this is turned and finished a pivot to fit the bearing.
repousse – (reh-poo-say1) A kind of decorative work on metal objects, in which a design is formed by punching or pressing portions of metal out from the inside or back of the object.
repousse punches – Steel punches, about 4″ long, of round, square and rectangular cross section. Generally domed and highly polished, they are used to push, by hammering, metal into desired shape and design. To outline the design, “tracers” are used; for background effects, matting tools are employed. Some repousse and chasing tools are interchangeable.
reproduction – 1. Gemology. Any imitation. 2. Jewelry, etc. See ANTIQUE REPRODUCTION.
resilient escapement – A lever escapement in which the banking of the fork or the pallets is against resilient surfaces to allow a cushioning effect in the event of overmotion of the balance resulting in the roller jewel striking the outside of the fork.
resin opal – Common opal with a resinous luster and a wax-, honey-, or ocher-yellow color.
resist – 1. Electroplating. Any lacquer to be painted on surfaces where no deposit of metal is desired. Most resists used are nitro-cellulose lacquers; occasionally, shellac dissolved in alcohol, or asphaltum varnish. 2. Protective, acid-proof coating which covers area where no etching is wanting. See ETCHING.
resistance – 1. Opposition to the passage of a current, causing electrical energy to be transformed into heat. 2. Representing the type of heating device or furnace used in heating or melting of metals.
resistor – In electrical timepieces, a coil or conductor that will resist a flow of electricity, measured in ohms.
rest – 1. A term used by European writers on horology, denoting the type of contact at the locking points in escapements; as: “frictional rest,” “tangential rest,” etc. See ESCAPEMENT. 2. A support for a cutting tool in a lathe. See SLIDE-REST; T-REST.
resting barrel – Such as used in some 23-jewel railroad watches where the barrel is stationary, the power being transferred from the mainspring arbor.
Retail Jewelers of America, Inc – Nationwide U.S. trade association of retail jewelers, with state-association affiliates; founded in 1906; sponsors International Jewelry Trade Fair and co-sponsors Permanent International Jewelry Exhibit, both in New York.
retaining pawl – A click which prevents back-slippage of an advanced wheel.
retinalite – A honey-yellow serpentine with a resinous luster.
reversed fuzee – Motive power design in which hooking of the mainspring is reversed so that the chain pulls on the side of the fuzee between center pinion and fuzee center, to lessen friction on fuzee arbor pivots.
reversible case – A watch case made with an inner case with glass over dial, which fits into an outer case of which one side is open and the other has a hinged lid with lift-and-catch-springs as in a hunting case; the movement in the inner case can be turned either way, to form at will an open-face or hunting-cased watch.
rheostat – A device for regulating the strength of an electrical current by varying the resistance.
Rhine diamond – Said to be a misnomer for colorless beryl.
rhinestone – Theoretically, quartz (Rheinkiesel) from the gold washings along the Rhine in Baden: but-as generally used today-glass. Often, in Germany, parti-colored green-white-red brilliants sold as tourist souvenirs.
rhodium – A white metallic element of the platinum group, used as an alloying addition to platinum and palladium jewelry and chemical ware, and as an electroplate finish. Because it is the most reflective of the platinum metals, harder and whiter even than platinum, and highly resistant to corrosion, it is widely used for plating. Silver, white gold and platinum can all be rhodium plated. Melting point about 1966° C.; specific gravity 12.4; chemical symbol Rh. See also PLATINUM GROUP.
rhodizite – An exceedingly rare mineral of interest to collectors. It is a potassium (caesium-lithium) aluminum borate which has been found in rose-colored masses in the Urals and in greenish crystals, with tourmaline, in Madagascar. Refractive index, 1.69; specific gravity, 3.40 and hardness, 8; luster vitreous to adamantine.
rhodochrosite – (ro-do-kro’site) Manganese carbonate, one of the ores of manganese. It is a soft mineral, hardness about 4 but has an attractive pink color and has been used as a decorative stone. Banded masses have been found in the Argentine and marketed under the name Rosinca or Inca Rose. One of the four minerals depicted in the special set of mineral stamps issued by the U.S. Post Office on June 13, 1974. Transparent faceted stones of this soft but colorful mineral have been cut from Colorado and African material. In jewelry the banded Argentine masses have found popularity as pink cabochons. Being carbonates, like malachite, they must be handled with caution; soluble in acid, they cannot stand pickling solution.
rhodoid – An amber imitation made of cellulose acetate.
rhodolite – A rose-red to pale violet variety of pyrope garnet coming from Macon County, N.C. A similar stone has been found in Ceylon (Sri Lanka) and Tanzania, in rather large (to 50 carats) stones.
rhodonite – (ro’don-ite) A pink manganese silicate, opaque to translucent. Frequently used as a decorative stone, especially in Russian carved objects, as in Easter eggs, plates, etc. Hardness, about 6; specific gravity, 3.4-3.68. Found at many localities and associated with some ores. Fowlerite and bustamite are varieties. Clear gems have been cut from transparent crystals found in the galena (lead ore) at Broken Hill, N.S.W.
rhombic dodecahedron – The ordinary dodecahedron of the isometric system, which has rhomb-shaped faces. The name distinguishes this common garnet and diamond crystal form from the pentagonal dodecahedron characteristic of pyrite (pyritohedron).
rhombic facet – A facet with four sides of equal length, having its angles oblique.
rhombohedral system – A subdivision of the hexagonal system characterized by the three-fold, instead of a six-fold, symmetry. It is developed from the hexagonal by the extension and suppression of alternate faces. Many minerals, including quartz and tourmaline, are in this subdivision.
rhomboid facet – A parallelogram-shaped facet in which the angles are oblique and the adjacent sides are unequal.
R.I. – REFRACTIVE INDEX.
riband agate – Agate with wide parallel bands.
riband jasper – Jasper with broad ribbon-like stripes of alternating colors.
ribbonstone – An Australian banded white and brown jasper.
ricolite – Banded verde antique.
riffle file – Small hand file with curved ends of various shapes and cuts, for filing the center of flat or concave surfaces. Used chiefly by die makers.
right-angled escapement – Lever escapement in which the balance center is planted on a line that stands at a right angle to a line that connects the pallets center and the escape wheel center. See STRAIGHT-LINE ESCAPEMENT.
rim – 1. The circular part of a watch balance, carried by the arms. See SEGMENT. 2. The center of a watch case, to which the lids of backs and bezels are hinged.
ring – Jewelry in form of circlets, usually of precious metal; earrings worn suspended from the ear-lobes, and finger-rings worn on any of the fingers, also (rarely) on the thumb. Finger rings are of ancient Egyptian origin. First often associated with superstitions or religion, their uses later included signets or seal-rings for personal identification and signatures on documents; today, finger rings are probably used mostly for personal adornment, but often combined with such purposes as being tokens of betrothal, marriage, school or college matriculation, membership in fraternal organizations, or to display family crests, or birthstones, etc. Many rings are worn as mountings for gem stones, both as ornament and as a convenient way of carrying realizable assets of value. Also see JUMP-RING; SPRING-RING.
ring adjuster – A gold spring with ears to clamp inside a finger-ring that has to be oversized to go over an enlarged knuckle, used to keep the ring from turning on finger; or to decrease the size of a ring without cutting and resoldering it.
ring agate – Agate with concentric rings, but without the great color contrasts characteristic of eye agates or Aleppo stones.
ring arounds – American pearl fishers’ term for pearls with a discolored band around them.
ring bender – A bench machine with dies for forming metal strips into circles for making finger rings, etc.
ring blank – First operation in ring-stamping produces a circle of metal that will undergo further treatment to produce a finished ring.
ring buff – A tapered felt buff for polishing inside of rings.
ring collets – Collets in half and full sizes for holding rings in faceting machines or in diamond-polishing lathes.
ring clamp – Handvise to hold rings during setting of stones, made of wood, with leather-lined jaws at one end and a wooden wedge at other end to close the jaws.
ring cutting plier – A levered device for holding and cutting through a ring by means of a manually operated circular saw. Used primarily for removing ring from swollen or oversized finger.
ring sizer – Machine on which rings can be stretched without soldering. There are also devices that are used to reduce plain or wedding bands in size.
ring sizes – In the U.S. since 1874 or earlier, a set of numbers designating the inside diameter of a finger ring, expressed in decimal parts of an inch. The interval between full sizes is about .032″, between half-sizes about .016″, and between quarter-sizes about .008″. Rings for infants usually range from sizes 000 to 2 (.388 to .522), for children from 2% to 4 (.538 to .586), for women from 4Vi to TA. (.602 to .698), for men from 7% to 13 (.698 to .874). Table shows U.S. sizes, as listed in the National Bureau of Standards “Recommended Commercial Standard for Finger Ring Sizes” (1951). British ring sizes substitute letters for numbers, ranging from A, equivalent of the U.S. 1/2 size, to Z, and usually though not always, the interval between the British letters is the same as a U.S. half-size. Continental ring sizes are designated by millimeters, the French measuring millimeters of circumference and the German millimeters of diameter.
ring stamp – A curved punch of hardened steel with reverse of a quality stamp or mark, engraved in the end. Used for stamping such marks inside a ring shank.
ring stamping machine – Used for rolling die impression in ring. Outlasts hammering stamps and prevents marring of ring.
ring stick – A graduated rod, about 7.5″ long, attached to a handle, used for measuring sizes of rings by pushing a ring on the stick and reading the size mark on the stick nearest the middle of the ring shank. The graduated portion of the ring stick should be tapered uniformly and be made of suitable metal or plastic, rather than of wood.
ripe pearl – Pearl with a fine orient in contrast to those with a poor sheen known as unripe pearls.
river agate – Moss agate pebbles from stream beds.
river bort – Alluvial poor quality diamonds.
river diamonds – A widely and ambiguously used term; actually only alluvial diamonds are indicated by the word. However, it is sometimes used to mean the finest quality blue white stones; below the unusual Jager and above blue Wesselton or top Wesselton. A.F. Williams’ remarks (1924): “The so-called difference in character between the ‘river’ stones and the ‘mined’ stones cannot, with the information now available, be established, in fact evidence is outstanding that the majority of them are identical to the diamonds found in kimberlite. Most alluvial gravels carry some diamonds which cannot be identified as the product of any known known mine, but their presence is easily explained as being diamonds derived from undiscovered kimberlite occurrences.”
river diggings – Alluvial workings.
river pearl – Fresh water pearl.
river sapphire – Light-colored sapphire from the Missouri River in Montana.
rivet extractor – Special punch and stand for removing rivets quickly without cutting off heads.
riveting – Fastening parts together by pins through holes in parts, the ends of pins hammered into form of heads larger than the holes; or by using a bolt with a head on one end and the other end hammered into a rivet. Special kinds of riveting are used for fastening staffs to balances, by punching a circular rivet on a shoulder of the staff with its heading overlapping the upper end of hole in balance-arms center; or for attaching a wheel to its pinion by riveting ends of pinion leaves over the hole in center of the wheel.
riveting stake – A steel base upon which objects to be swaged or riveted may rest; an anvil.
rock crystal – 1. Gemology. Clear, colorless quartz, often masquerading under such names as Arkansas diamonds, Bohemian diamonds, Bristol diamonds, Cornish diamonds, Herkimer diamonds, etc. 2. glassware. In reality, a piece of quartz glass made by melting pure rock crystal at high temperatures. Such pieces are extremely rare and costly, and in modern usage, the term has come to denote high quality crystal glassware decorated with cuttings.
rocking bar – The bascule yoke in a lever-set watch which carries the intermediate wheels connecting the winding stem wheel or pinion with the setting or winding gears when the lever is operated. See LEVER-SETTING.
rock ruby – Misnomer for pyrope garnet.
rock turquoise – Turquoise matrix with small disseminated grains of turquoise.
Rocky Mountain ruby – Misnomer for red pyrope garnet.
Rockwell test – A system of testing and indicating numerically the hardness of metals, by an instrument that presses a diamond point into the metal and registers on a dial the depth to which the point penetrates; the softer the metal, the deeper the point will enter it, with the same pressures on the point.
Rodico – Trade name of a rubberish putty-like substance which is used to pick up tiny objects or remove lint or particles from watch parts or magnets.
rogueite – A greenish jasper found in gravel in the Rogue River, Oregon.
roller – Metal disc set concentrically on the balance staff, in which is set the roller jewel, and through which motive power is given to the balance by a lever escapement; the edge of the roller, with the guard-point, provides safety action in the escapement. The two forms of roller are the single roller, with one disc; and the double roller, with one disc for roller jewel and a separate disc for safety action. See FORK; LEVER ESCAPEMENT; ROLLER JEWEL.
roller crescent – The passing hollow or notch in a safety roller to allow passage of the guard pin in a lever escapement.
roller jewel – Pin, usually of ruby or sapphire, set perpendicularly in the roller, that works in the slot of the fork of a lever escapement, during unlocking of the escapement and impulse. See FORK; LEVER ESCAPEMENT; ROLLER.
roller jewel setter – Tool for holding in correct position a roller jewel, during the operation of cementing it in its hole in roller.
roller remover – Tool for applying pressure axially on roller tables, to withdraw them from balance staffs. The pressure is applied either by a screw or by levers.
roller-shake – The slight play or motion of fork and guard-pin between contacts on one side of lever against banking, and on other side of guard pin (or point) against roller edge.
rolling barrel – A machine for polishing quantities of metal articles inexpensively prior to electroplating; these are placed in a barrel, tub or bowl-type vibratory machine turned by motor power, and containing also abrasive powders and oil or water; the pieces of work rub on each other acted on by the abrasive. This process is used for work without sharp corners, and for which hand-polishing would be too costly. See TUMBLING.
rolling friction – The kind of friction that occurs in the action of gear-teeth against pinion leaves, etc. See FRICTION; LUBRICATION; SLIDING FRICTION.
rolling mill – A pair of hardened steel rolls, geared to turn together in a frame, the rolls adjustable toward each other, used in jewelry shops for reducing the thickness of bars and rods of gold and silver, forming flat sheet or wire.
rolling pinion – The action in some lantern pinions in which the pins are allowed to turn in their shrouds.
Roman gold – A finish on gold jewelry, etc., produced by matting or frosting the surface, then electroplating it with pure gold; the appearance of it is a soft, rich yellow without polish.
romanzovite – Dark brown grossular garnet from Finland.
rondelle – Small flat discs which separate the larger stones of a necklace.
rope chain – Chain for watches or jewelry, made of fine wire arranged in closely massed links to resemble rope.
rosaline – Thulite.
rose beryl – Morganite.
rose cut – Early type of diamond cutting, probably originated in India and introduced into Europe by the Venetians; now used only for small diamonds. This cut has a flat base, with a series of triangular facets terminating in a point on the top of the stone. Various forms are the Antwerp rose, 12 facets or less; the Half Dutch rose, 16 facets; the Dutch rose, 24 facets; the Double Dutch rose, as many as 36 facets. They may be circular, elliptical or oval. Stones cut in this way are commonly called simply rose diamonds in the trade; an undesirable usage because of the possible confusion of color with cut, rose cut is preferable. Also said to be applied to diamonds that are so small that they can only be slightly cut, if at all.
rose cutter – A milling cutter with cutting teeth on the rim of a hollow cylinder or rod.
rose de France – Brazilian term for amethyst of pale lilac hue.
rose engine – An engraving machine, for producing geometrical designs on jewelry, watch cases, etc., in the forms of engraved decorations called engine-turning, barley corning, etc.
rose fluor – Pink fluorite.
rose garnet – Incorrectly applied to rhodolite; also a trade name for the rock from Xalostoc, Morelos, Mexico, consisting of rosolite, vesuvianite, and wollastonite.
rose gold – A finish on gold jewelry, etc., on modeled or heavily chased or carved work, obtained by electroplating with pure gold, or dull red gold, then polishing the higher features of the design, to contrast this bright polish with the dull gold remaining in the lower parts of the work.
rose kunzite – A misleading term for pink synthetic sapphire.
rose moon stone – Pink scapolite from Burma.
rose pearl – 1. Fairly regular fresh-water baroque pearl with a good pink iridescent tinge. 2. Any pearl with rose overtone. A white-pink color is the most popular in America and some but not all other areas. Gold is the favorite in South America and Australia.
rose quartz – Pink quartz, commonly used as a decorative stone. Pale pink but well asteriated rose quartz has been used in the construction of imitation star sapphires. It is a pegmatitic variety of quartz and occurs in many places, notably Brazil and South Dakota.
rose recoupee – (ray’koo-pay’) Double Holland rose.
rosinca – See RHODOCHROSITE.
Roskopf – A designation for a type and grade of Swiss watches, named after George Frederic Roskopf, Swiss watch designer and manufacturer (1813-89), who in 1868 adapted the French pin-pallet escapement. It was characterized by an enlarged barrel intruding beyond the center of the movement, eliminating one train wheel, the cannon pinion friction arising from the enclosed minute wheel frictioned to the barrel cover. See PIN-PALLET ESCAPEMENT; PIN-PALLET LEVER ESCAPEMENT.
rosolite – Pink or rose-red grossular garnet from Xalostoc, Morelos, Mexico. Often the whole rock in which it occurs, where it is associated with yellow brown vesuvianite, white wollastonite and white calcite, is polished to make decorative slabs, also called xalostocite and landerite.
rosterite – Rose-red beryl from Elba.
rotary file – Round file, 1/2″ to 5/8″ in diameter and 1-1/2″ long with 1/8″ or 1/4″ shank. Used in drill press or flexible shaft machine for inside ring work. Made in medium and fine cuts.
rotary pivot polisher – See PIVOT POLISHER.
rothoffite – Yellow to brownish andradite garnet.
rotor – Horology. 1. In synchronous electric clocks, the rotating part turned by the electro-magnetic power of the fields, and geared to a reducing train that turns the hands; or the same part in the motor of an electrically-wound clock. 2. The oscillating weight of a self-winding watch, turning 360°.
rottenstone – An abrasive powder used in jewelry and watch work, comprising largely silica left over from weathered and decayed limestone. See TRIPOLI.
rouge – A product of iron oxide, pulverized and graded, used for abrasives in horology and jewelry work. The dark-colored coarser grains are marketed as crocus for grinding, the finer grains as rouge (French for “red”) for polishing steel and precious metals. Rouge powder is also mixed with wax and other binding substances to form bars or cakes, for conveniently applying it to buff-wheels on polishing lathes.
rough – Gemology. Uncut gem stones; both natural crystals and water-worn pebbles are included under this general term.
roulette – Hand-tool with rotating die, for producing millgraining or gemstone settings. See MILLGRAINING. 2. Engraved circular rolling mill used to impart design to rolled wire.
roumanite – Roumanian amber.
round bort – Brazilian ballas.
rounding-up tool – A modification of the wheel-cutter, for recutting teeth of wheels to correct slight errors of truth in running of a gear wheel. This device is designed either as (Swiss type) a self-contained machine on a base and driven by a hand-wheel, or as (American type) an attachment for a watchmaker’s lathe.
round-nose pliers – Pliers with cylindrical jaws, usually tapered, for bending metal into circular forms; or for holding objects of such form.
rounds – The rods or wires that act as leaves in a lantern pinion. See LANTERN PINION.
roundstones – A diamond crystal classification, rounded white to yellowish stones with curving faces.
royal pendulum – A clock pendulum that beats seconds.
royal topaz – Blue topaz.
rozircon – Misleading name for pink synthetic spinel.
rubasse – Some authorities apply this name to a crackled quartz which is artificially stained red, others apply it to a quartz containing red flecks of hematite. Also called rubace.
rubbish – A diamond classification, the next to poorest quality. Such stones can be used only industrially, as for tools, etc.
rubellite – (roo’bel-lite) Pink to red tourmaline.
rubicelle – An orange-red spinel.
rubitine – Diamantine mixed with jeweler’s rouge.
rubolite – Red common opal from Texas.
ruby – Red corundum, the color being due to chromium impurities. It grades into pink sapphire and no hard and fast line between the two can be drawn. See ANTHRAX; ASTERISM; BEEF BLOOD RUBY; BURMA RUBY; CARBUNCLE; CERAUNIA; CEYLON RUBY; CHALCEDONY PATCHES; PIGEON BLOOD RUBY; SILK; STAR SAPPHIRE.
ruby balas – Red spinel.
ruby cat’s eye – A stone which is related to the star ruby, but in which there is a rounded or elongated opalescent light, in place of the distinct arms of the star.
ruby cylinder – A C-shaped ruby attached to the staff from which it was underslung and acted upon by the escape wheel, used in Breguet’s cylinder escapements.
ruby file – A strip of ruby or other equally hard stone mounted in a handle, with a ground surface used as a lap for making alterations on hardened steel parts of watches.
ruby glass – A red glass, the most popular of which is colored by gold chloride. After a first quick cooling it is greenish to colorless; it becomes red only after a second careful heating.
ruby juice – Clear red lacquer sometimes used to coat the underside of some stones to improve their color.
ruby matrix – A red corundum, green amphibole (smaragdite) mixture found on Buck Creek, Clay County, N.C. It is attractive for cabochon cutting, but, because of the disparity in hardness of the two minerals, it is difficult to polish. Also called Mother of Ruby. See GOODLETITE.
ruby roller – In a high-grade duplex escapement, a hollow cylinder of hard stone forming the locking part of the balance staff, in which is cut the passing-notch for the locking teeth of escape wheel. The ruby roller is cemented to the thinned body of staff that passes through the roller.
ruby spinel – Red spinel. An undesirable usage because of possible confusion with ruby.
ruby tin – Red cassiterite, the tin oxide. Some stones have been cut of this material for collectors.
Rumanian amber – An amber similar to Baltic amber, found in some quantities and in considerable sizes at several localities It is more expensive than the Baltic; greenish, bluish and blackish specimens are found, with a strong fluorescence. Some with many cracks and flaws have a beautiful golden luster and are highly valued but the annual production is rather small. Rumanite is another name for this material, which is a retinite rather than a succinite; mineral varieties are almaschite and delatenite. See BALTIC AMBER.
runners – A center or centered receptacle-rest for pivots being polished.
Russian crystal – Selenite.
Russian lapis – A misnomer, generally, for Afghani lapis which probably arises from its frequent marketing through Russia. Confusing because there is a Siberian lapis occurrence, which generally is paler in color.
ruthenium. A white metallic element of the platinum group, used mainly as a hardener for platinum or palladium. Melting point above 2400° C.; specific gravity 12.2; chemical symbol Ru. The 5 per cent ruthenium-platinum, which resembles 10 per cent irido-platinum in most working properties, came into use as a jewelry metal during World War II. The alloy 95 per cent palladium plus small amounts of rhodium and ruthenium, is also suitable to jewelry purposes. Ruthenium is highly resistant to atmospheric corrosion and to ordinary acids, including aqua regia, but when strongly heated a volatile oxide of unpleasant odor may be formed. See also PLATINUM GROUP.
radiated quartz – (roo’til-late-ed) Sagenite. See RUTILE.
rutile – (roo’teel) Titanium oxide, red brown to black in color. It is sometimes cut as a gem for collectors but has no gem interest for the public. The dark color from impurities (iron) militates against any popularity for it; this is unfortunate because its refractive index is very high: 2.62-2.90; hardness, 6-6l/2; specific gravity 4.2-4.3. It is found principally in igneous and metamorphic rocks and is sometimes a source of titanium. It is now made synthetically. See TITANIA.
sabalite – Trade name for a banded green phosphate mineral possibly variscite, from near Manhattan, Nev. See TRAINITE.
safe edge file – A file with smooth surfaces other than the surface which cuts.
safety-action – In a lever escapement, the action of the guard-point or guardpin on the fork, with roller-table edge, to prevent the fork going over to the wrong side of the escapement when a watch receives a shock sufficient to overcome the force of draw and throw the lever away from its rest against a banking; also called “guard-action.” See FORK-AND-ROLLER ACTION; LEVER ESCAPEMENT.
safety barrel – A mainspring barrel separated from its main wheel and connected to it only through the mainspring. Should the mainspring break, the explosive backsurge would not cause a shearing of the main wheel teeth or the train wheel teeth and pinion leaves. See MOTOR BARREL.
safety catch – A pin-tongue catch for brooches, pins, etc., with a tongue or bar that can be operated to close the opening in the catch, to prevent the accidental opening of the pin and loss of the jewelry.
safety chain – A short chain connected to one end of a bracelet with a spring ring at its end to connect with a link at other end of bracelet. A device to prevent loss of a bracelet should the catch open or become defective.
safety-pinion – A center pinion that unscrews on the center-arbor if a mainspring breaks, to protect the train from shock and breakage.
safety roller – The smaller of the two roller tables in double-roller lever escapement, the sole function of which is to cooperate with the guard-point on the fork to provide safety action; the larger roller table in a double-roller escapement is for transmitting impulse only, from fork to balance.
safranite, saffronite – A coined trade name, proposed by a European trade conference for citrine quartz. Topaz saffronite was to be a preliminary step. However, the word has not caught on.
sag – The distortion of form of a hairspring with watch in vertical (“on edge”) positions, caused by the effect of gravity on the coils.
sagenite – (sayj’e-nite) A reticulated variety of slender prismatic rutile needles, often included in quartz.
sagenitic quartz – Clear quartz, rock crystal or smoky, with included sagenitic rutile needles, normally; but the term has been extended to cover all sorts of prismatic inclusions, like tourmaline, actinolite, goethite, epidote and so on. Synonyms are rutilated quartz, fleches d’amour, Venus’ hairstone, Cupid’s darts, etc. Localities include Switzerland, Brazil, Vermont and North Carolina.
Saint Stephen’s stone – A white chalcedony, full of little red spots, formerly venerated as dyed by its employment in his martyrdom.
sakal – Egyptian name for amber.
sal ammoniac – Ammonium chloride; a salt used for many purposes in jewelry work and electroplating, in dry and wet cells for generating electricity and as a soft solder flux.
salam stone – An oriental name for sapphire, said by some to be reserved for a variety found in small hexagonal pale red or blue prisms, found chiefly in Ceylon.
Salamanca topaz – Misnomer for a fiery-colored citrine from the Spanish province of Salamanca.
salt water pearl – A genuine Margaritifera pearl.
samarskite – (sa-marr’skite) A velvety black, orthorhombic mineral of the rare earth group, often radioactive. Hardness: 5-6; specific gravity: 5-6-5.8. Sometimes cut as gem for collectors.
sammyi – Native Burmese name for the residual weathered mass in which rubies are found. See BYON.
sandaster, sandastras, sandastros – Several versions applied to a red, hematite-filled, aventurine quartz. Sandersos is supposed to be green aventurine.
sand bag – A cushion-like bag, filled with fine sand and covered with leather; used by engravers to rest their work on or to prop the work up at a convenient angle and by silversmiths to hammer metal to required shape.
sand-blasting – Method of producing on metal, glass, etc., a matted or frosted finish by holding the work against a stream of sharp sand driven by a jet of compressed air.
sand-casting – An adaptation of foundry molding to use in the jewelry shop, for duplicating a piece of work, used as the pattern, to make a mold in damp sand; then pouring melted metal into the dried mold. See CUTTLEFISH BONE CASTING.
sander – A horizontal or vertical wheel used in the operation of “sanding” a gem.
sanding – The process immediately preceding cabochon polishing, in which the deep scratches of the cutting wheel are removed. Garnet paper, emery cloth or silicon carbide cloth may be used in the operation.
sand pearl – Irregularly shaped natural pearl that may have a large sand or clay nucleus.
sand shell – The shell of an elongated, flat variety of fresh water mussel, the Lampsilis, which attains six inches in length and is in considerable demand for buttons.
sandstone opal – One of the miners’ varieties of opal from Queensland; a variety with concentric shells of sandstone and soft clay, with layers of opal between or in cracks. In general, a poor variety of opal. See BOULDER OPAL.
sandy sard – Sard with numerous darker opaque spots.
sang-i-yeshen – A dark green compact bowenite serpentine resembling nephrite, from northwestern China.
sanidine – (san’id-een) A glassy variety of white or yellowish orthoclase feldspar, commonly tabular, hence the name, occuring in volcanic rocks.
sapphire – (saf’ire) In a restricted sense, gem blue corundum, though in common usage it means any gem corundum other than a ruby. Those who would like to restrict the word to the blue variety point out that in the ancient usage, when it meant an entirely different stone, it was a blue stone that was so denominated. See CORUNDUM; BENGAL AMETHYST; STAR SAPPHIRE; ASTERIA; GIRASOL SAPPHIRE; CEYLON SAPPHIRE; CASHMERE SAPPHIRE, etc.
sapphire cat’s-eye – Sapphire with inclusions running in a single direction, so that a single transverse light streak is seen. See STAR SAPPHIRE.
sapphire file – See RUBY FILE.
sapphire glass – Said to be a blue glass of exceptional hardness but of unascertained composition.
sapphire quartz – Misnomer for AZURE QUARTZ.
sapphire spar – Misnomer for Kyanite.
sapphire spinel – Erroneous and misleading name for blue spinel.
sapphirine – (saff-ear-een’) 1. A rare magnesium aluminum silicate, occasionally blue in color but it has not, to date, been found in specimens suitable for cutting, being, at best, translucent. However, the name has been improperly used for a number of other substances including blue chalcedony, blue quartz and blue spinel. 2. An abrasive powder used in horology for grinding and polishing hardened steel. The grains are chemically produced crystals of the element boron. The product is of same nature as diamantine, the only practical difference being the blue tint of sapphirine. The powder is sold in two grades or grain-sizes; number 1 for grinding and number 2 for polishing.
sapphirine chalcedony – See SAPPHIRINE.
sapphiros – An ancient name for lapis lazuli, and sometimes azurite. See SAPPHIRE.
sard – Dark red to brown onyx. The term, which came from the Grecian name for a locality (Sardis), has been variously interpreted and in Biblical times referred to a red stone, like carnelian. See AGATE, BANDED AGATE, CHALCEDONY, CARNELIAN, SARDONYX.
sardoine – Said to be a western name for dark-colored desert carnelian.
sardonyx – (sard-on’iks) Agate consisting of layers of brown (sard) and white. Not a synonym of sard or carnelian, but since one rarely hears of “carnelian onyx,” one must assume that redder colors appear in the sardonyx than ever are seen in sard proper. However, to the trade it is a reddish to reddish brown variety of onyx, often the result of cutting dyed chalcedony, in which the dye has not penetrated white bands in the original material.
sardstone – The name given to the horizontal layers in the Brazilian agate amygdules, which are used as a source of sardonyx for cameos, etc.
sarduin – A chalcedony artificially colored brown through heating after soaking in a sugar water solution.
satin finish – A finish on jewelry, etc., given by dulling the polish by scratch-brushing, sandblasting or chemical treatment, producing a surface of metallic color, but with a soft, pearl-like luster instead of bright polish.
satin spar – Fibrous gypsum, or incorrectly, fibrous calcite. On polishing, it develops a silky translucence, and has been used for Easter eggs, etc. Very soft, easily worked and easily scratched. See ATLAS SPAR; FEATHER GYPSUM; FEATHER WHITE, etc.
saussurite – Another of the stone materials carved in China and generally included as jade substitutes. Saussurite is a rock, apparently an alteration of some earlier gabbro by hydro-thermal solutions which transform the primary minerals to zoisite and plagioclase feldspar, often with minor amounts of diopside, chlorite and possibly clino-enstatite. Carved masses coming from China have a granular look, much like jadeite, with green areas to produce excellent simulations. As a rock-like material, it is widespread in nature and it is very likely that many Oriental carvings are made from this material, which has no really fixed composition, being a rock rather than a mineral.
Savage two-pin escapement – A lever escapement with very wide fork slot. Two widely separated roller pins perform the unlocking, a vertical pin on the fork providing the impulse into a slot in the roller and between the pins. This escapement claims as its virtue the unlocking taking place closer to the line-of-centers.
savonnette – French for hunting-cased watch. See HUNTING-CASE.
saw – 1. Tool for cutting material by action of a toothed edge. See CIRCULAR SAW; HACK SAW; JEWELERS’ SAW; SAWBLADES. 2. In gem cutting, sawing is a sectioning process accomplished with the aid of an abrasive-charged disc. Prior to development of the circular diamond saw about 1900, diamonds were sawn laboriously by a diamond-charged bow-saw. The circular saw is a bronze disc, 3 to 4″ in diameter, charged with diamond powder, turning at speeds of 4500 to 6500 r.p.m. Sawing a quarter-carat rough takes some 40 minutes, a carat stone two to eight hours unless a knot is encountered. Other gemstones may be sliced with carborundum or softer materials. Wire saws, oscillating blade saws, etc., are used on other stone materials, but in any case the principle is quite different from that of a toothedged wood or metal saw.
sawblade dispenser – A device consisting of a series of tubes or openings to hold sawblades of various sizes.
sawblades – For use in jewelers’ sawframes; narrow flexible steel strips with teeth cut on one edge, fastened at both ends to clamps of the sawframe, which stretches the blade at considerable tension in use. Blades are graded in sizes, from the largest in cross-section, called No. 6, to No. 1, smaller; then still smaller No. 0 to No. 8/0; these are the sizes regularly used. Most sawblades are made of square cross-section form, called “square” blades, for sawing both straight and curved lines. The blades of oblong cross-section, called “flat,” for sawing straight lines only, are not much used in horology or jewelry work.
sawframe – An adjustable frame in which a saw-blade is clamped at both ends. Used by jewelers and watchmakers for cutting metal and producing profiled or pierced work.
Saxony chrysolite – Topaz.
Saxony diamond – Misnomer for topaz.
Saxony topaz – True topaz from an interesting occurrence in the Schneckenstein (snailstone), in Vogtland, Germany. It was the source of the topaz in the Saxony crown regalia. The stones were found in small pockets with quartz, in pale yellow crystals, rarely much over an inch across.
scaife – (skife) Horizontal diamond polishing wheel invented in 14th Century and powered successively by hand, horse, steam and electricity. See LAP.
Scandinavian Diamond Nomenclature – A system of definitions and standards for grading diamonds for proportion, color and clarity, approved in 1970 by Scandinavian jewelers’ associations. With its goal a uniform “diamond language” for Denmark, Finland, Norway and Sweden, a 52-page manual was published in each of those tongues, as well as in English and several other languages. Herbert Tillander, C.G., F.G.A.r of Helsinki, Finland, headed the committee.
Scandinavian D.N. Standard Cut – Proportions for an ideal brilliant suggested by the Scandinavian Diamond Nomenclature Committee and approved in 1970 by representatives of the jewelry trades in Denmark, Finland, Norway and Sweden. The proportions of the crown are closer to those of the so-called Eppler fine cut, proposed by Dr. W. F. Eppler in 1940, than they are to those calculated by Marcel Tolkowsky in 1919. The latter, long also known as “American Cut” or “Ideal Cut,” were endorsed in 1975 by the American Gem Society. In the Scan D.N. Standard Cut, the table is wider, the crown is slimmer, and the table-to-culet depth is less than in the American Cut. See AMERICAN BRILLIANT CUT; EPPLER, W.E.; TOLKOWSKY, MARCEL.
scape wheel – The wheel whose teeth apply power to the pallets of a detached escapement, or to the impulse parts of balance staffs in frictional escapements; the escape-wheel.
scapolite – (scap’o-lite) A group of minerals, sodium-calcium aluminum silicates, crystallizing in the tetragonal system, sometimes in transparent crystals, with a hardness of 5-6, specific gravity of 2.66-2.73; white, yellowish, pale violet, pink, gray, etc., in color. There are two gem varieties, a clear yellow occurring in Brazil and Madagascar, and a translucent white to pink, which cuts with a cat’s eye, coming from Burma. They are commonly called pink moonstone. Very rarely, clear pink stones have been found in Burma.
scarab – Jewelry. A representation of the Scara-baeus beetle, which the ancient Egyptians regarded as symbolic of resurrection and immortality, and which they modeled of gold or glazed clay or carved from precious, semiprecious or non-precious stones, for setting into rings, armlets, neck ornaments, etc. In swivel rings, scarabs were cut on the under side with an intaglio design for use as signets. The custom of wearing scarabs spread through the ancient Mediterranean world and has extended to modem times.
scauper – A tool having a semi-circular face, used by engravers to clear away the spaces between the lines of an engraving.
Schaumburg diamonds – Misnomer for rock crystal from cavities in a marl near Schaumburg, Germany.
schield – A three-faced simple form of Holland rose.
schiller – (shil’ler) A peculiar, almost metallic, luster seen in certain directions in some minerals, caused by the presence of tiny oriented crystals or cavities on definite planes of the mineral. In this sense it is distinct from labradorescence which is considered to be caused by interference. See BRONZITE; HYPERSTHENE; BATISTE; SUNSTONE, etc.
schiller chrysolite – Chrysoberyl (cat’s-eye).
schiller obsidian – Grayish, reddish or greenish obsidian with microscopic parallel inclusions which give a schiller effect to the stone.
schiller quartz – Quartz cat’s-eye or “occidental cat’s-eye.”
schiller spar – Bastite.
schnide – Glassy, blue common opal, constituting 90 per cent of the opal mined in Queensland, Australia.
schorl – (shore’ll) Common black tourmaline.
scientific brilliant – Erroneous and misleading name for synthetic white sapphire.
scientific emerald – Erroneous and misleading name for the green beryllium aluminum silicate glass product of the fusion of beryl, plus chromic oxide, in an attempt to make imitation emeralds with the properties of the genuine.
scientific gem – Misleading term for “artificial.” Usually glass, the “scientific” gem differs in composition from the stone it imitates.
scientific ruby – Early synonym for synthetic ruby, the major development of which was announced in 1902 by Auguste Victor Louis Verneuil. The term scientific was applied later also to the Hope synthetic sapphire, as well as, erroneously, to imitations of glass.
scientific sapphire – Misnomer for blue glass.
scientific topaz – Misnomer for the pale pink synthetic sapphires of the early experiments in ruby synthesis.
scintillation – The flashing of light from the facets of a stone, when the stone is turned or in motion, or when its observer or its light source is in motion. The Jewelers Manual (GIA) says that the degree of scintillation depends upon: (1) the number of facets that will reflect light to the eye as the stone is moved about (i.e., the number of individual reflections); (2) the quality of the polish of the facets, and (3) the brilliancy of the stone and thus the degree to which light is returned to the eye after refraction into the stone and back out through the crown.
scissor cut – A modification of the step cut, the long facets broken by diagonal corners into triangular facets, the stone remaining oblong in outline. Used on topaz, beryl, amethyst and tourmaline, it slightly increases the brilliance of those low index stones.
sclerometer – (sklare-rom’eet-er) An instrument for the accurate measurement of hardness, by measuring the scratch or indentation made with a diamond point, at a definite pressure.
scoopstone – Amber dredged from the Baltic Sea, in East Prussia.
scorper – A steel tool used by stone setters and engravers for engraving or tracing. It is used by stone setters to raise beads or fit stones. They have different shapes, flat, half-round or knife-edged.
scorpion stone – Coral or jet, ancient remedies for the sting of the scorpion.
Scottish pearl – Fresh water pearl from Scotland.
Scottish topaz or stone – Misnomer for Cairngorm.
scrap – A class of jewelry-shop waste, cuttings of precious metals, large enough to sort for re-melting, differentiated from filings, sawdust and other small waste that has to be sweep-smelted and refined to recover it for use. See LEMEL.
scraper – Triangular-shaped tool with smooth sides and extremely sharp edges, culiminating in a convex point. The sharp edges are used for scraping surfaces and removing burr edges, a. Case scraper. A hard steel rod with three sharp, hollow edges for shaving the inside edges of watch cases to allow exact fitting of the movement.
scratch brush – A brush with fine metal wires for bristles, made in form of handbrushes, or wheels for use on jeweler’s lathe; for cleaning work or for producing a matt finish on soft metal surfaces.
screwback – See EAR SCREW.
screw case – Watch case in which the back and bezel are held to the center by screw threads, cut on the shoulder-wall of center, and inside the back and bezel rims.
screwcutting lathe – A type of lathe in which the cutting tool is held in a mechanical rest and moved by a leadscrew, as in a sliderest. See SLIDEREST.
screwhead file – A file of thin steel with teeth cut on edges, for filing slots in screw heads.
screwhead tool – A hand lathe with laps to polish the heads of screws.
screw plate – A steel plate, drilled with a graded series of holes of various diameter, the holes tapped with screw threads and usually slotted at opposite sides to form cutting edges of the profiles of the threads; the plate is hardened; it is the principal means used by watchmakers for cutting threads on screws and for making taps.
screw thread – The helical or spiral ridge of a screw.
scriber – A pointed steel rod in handle, used by engravers for marking out work, and by watchmakers for laying out outlines of work for sawing, etc.
sea amber or sea stone – Amber which has been dredged up or collected on the Baltic beaches, with the altered crust worn off. Mined stones are now washed and worn in a sand water mill, so that the same effect is accomplished artificially.
sea foams – Meerschaum.
seal sapphire – Brown silky sapphire, commonly Australian.
seamless – A ring or tube made of one piece, without a seam. See JOINT WIRE.
sea mussel – The pearl-producing genus of Mytilidae.
sea opal – Solid masses of white opal from the White Cliffs, 60 miles north of Wilcannia, New South Wales; often mainly common opal with bands of the precious.
sea pearl – Salt water pearl, in contrast to the fresh water mussel pearls.
seaweed agate – A fanciful term for chalcedony with red, green or brown “growths” within them. Moss agate would be a better term.
second – One-sixtieth part of a minute. Seconds are seen on ordinary watch dials as divided into fifths; on marine chronometer dials, as divided into halves; on astronomical recording chronographs as divided into hundredths; and on micro-chronographs as divided into thousandths. See TIME.
secondary compensation – Devices used on bimetallic compensation balances of marine chronometer, to minimize middle-temperature error. See MIDDLE TEMPERATURE ERROR.
second bye – Just below first bye and above light off-colored, in diamond classification. Bye means a pale yellowish green or gray green tone.
second Cape – In diamond classification, just after first Cape and before first bye, Cape being almost pure white, with a slight yellowish tone.
secondary deposit – A deposit of a mineral formed through alteration of some pre-existing formation. Gold, diamonds, or corundum in gravels are secondary deposits, having been formed from the alteration, decomposition and removal of the original host rock, the primary deposit. Malachite and azurite, which form through the alteration of primary copper sulphides, are found in almost the same place as the original ores, but are exclusively secondary minerals.
second-hand – The hand on a timepiece dial that indicates the 60 seconds of a minute; usually it is on a prolongation of the lower pivot of the fourth pinion in a watch, or on the escape-pinion in a clock. See also SWEEP-SECONDS.
seconds bit – Small circular plate that forms the dial for the seconds hand in a single-sunk or double-sunk dial, cemented or soldered into an opening in the main plate of dial.
seconds pendulum – A pendulum beating seconds.
secret signature – Breguet, to thwart those who forged his name to their inferior watches, devised a method of scribing a small, almost invisible signature and serialization number on his dials, usually below the figure XII, seen by magnification under certain light-angles.
sectional plating – In electroplating, the depositing of extra thickness of metal at places that are subject to the greatest wear; these points are heavily plated first; then the entire article is plated and finished.
sector – A gauge showing the proportions between wheel teeth and pinion leaf numbers for comparative diameters. It is composed of two scaled, flat bars pivot-joined at one end and connected at the other by a metal arc-guide, sometimes marked accordingly.
sector watch – A timepiece in which the movement of the hands is limited to a sector of a dial, which itself may be a sector of a circle. After the hands reach the limit of the sector, they jump back to their starting position.
sedimentary rocks – One of the three types of rocks studied by geologists. Sedimentary rocks are derived from the weathering of earlier rocks, such as plutonic or igneous rocks, and the deposition and consolidation of their fragments into layered and sorted beds. In time, great thicknesses of sediments can accumulate, thousands of feet, and in them are many economically useful substances, like coal and oil, as well as fossil remnants of earlier life forms. See IGNEOUS ROCKS; ME-TAMORPHIC ROCKS.
seed – A small deposit of chemical materials. It is an imperfection in glass and, hence, a flaw.
seed pearls – Small pearls less than 1/4 grain in weight.
See-through mold compound – Trade name for a transparent compound used for flexible molds for wax injection. This material permits the mold maker to see the model while cutting it, requires no vulcanizing and is cured in oven.
segment – A plane figure enclosed by the chord of a circle, and the arc cut off by the chord. This term is used to denote each portion of the rim of a watch balance, separated from other portions by balance arms.
selenite – (sell’en-ite) Transparent, colorless gypsum crystal.
selenium – A photo-voltaic cell of selenium sandwiched between two electrodes, used as solar-energy cells or rechargers in some electrical timepieces.
self-contained – English term for class of electric clocks driven by primary-cell batteries, so they do not require service current from an outside source; in U.S.A. called “battery-driven” clocks.
self-winding – 1. Class of watches with mainspring wound by a pedometer-weight, that operates a click-and-rachet attached to the barrel arbor; also called automatic watch. See PEDOMETER. 2. Class of clocks driven by weight or spring, wound periodically by an electric motor automatically started and stopped by the clock mechanism; differentiated from electric clocks driven by an A.C. motor. See SYNCHRONOUS CLOCK.
sellers thread – A screw thread with flat crests and bottom. The U.S. standard type thread.
semi-carnelian – Yellow chalcedony.
semiconductor – A chemically treated solid material, a transistor or diode, usually made of germanium and silicon, with electrical conductive capacity midway between that of a metal (conductor) and an insulator. Semiconductors play much the same role in electronic products as vacuum tubes did in radios and TVs.
semi-equidistant – A compromise between the circular escapement in which the pallets are set on a circle emanating from the pallet center and the equidistant escapement in which the distance from the entrance corners of both jewels to pallet center is the same.
semi-mounting – A mounting that is set with only its small stones but has not yet received its center or main stone. Sec MOUNTING.
semi-navette – A popular “fancy” shape for cutting gemstones; half of a navette or marquise.
semi-opal – An intermediate variety of partially dehydrated common opal with a duller luster. A rather indefinite term of no particular significance; some consider it synonymous with common opal.
semi-precious – The second, and largest, of the three categories into which gemstones have been divided by traditional usage, as distinct from precious and decorative. The former group includes diamond, emerald, ruby, sapphire and pearl, as well as alexandrite, black opal, cat’s-eye, demantoid and jadeite. Stones are regarded as semi-precious, rather than precious, for one or more of the following reasons: relative softness, inferior brilliance, comparative abundance, unfamiliarity, or fashion. They vary widely in price from costly tanzanite, red tourmaline, green garnet and golden-orange precious topaz to the lovely and almost regrettably common amethyst and chrysoprase. However, the term is not to be recommended; it is often confusing because low-quality emeralds, for instance, can be bought more cheaply than some amethysts.
senaille – (sen-iy’ya) Small diamond splinters set around larger gems.
sepiolote – (seep’ee-o-lite) Meerschaum.
serpentine – (ser’pen-teen) A hydrous magnesium silicate of extremely variable appearance, with numerous names. It is commonly greenish or yellowish in color, though it may be brown, black, reddish, etc. Its hardness is 2-1/2 to 4, rarely up to 5-1/2. The common and best asbestos, chrysotile, is a variety of serpentine. Precious serpentine is a particularly compact and translucent green variety resembling nephrite, as does bowenite. It commonly forms through the alteration of primary magnesium silicates, often as a late phase of the original igneous activity by which the original perodotitic rock was formed. See KOREAN JADE, FALSO-NEPHRITE, SANG-I-YESHEN, SOO CHOW JADE, TANGIWAI, VERD AN¬TIQUE.
serpentine jade – A naturally light yellowish gray serpentine commonly dyed with analine colors to a fine jade green hue. Also applied to a naturally green serpentine, bowenite, which resembles nephrite in color and texture, but which is, of course, appreciably softer.
serpents’ eggs – Ancient Gallic glass beads, traditionally thought to be generated by many serpents congregated together, who shot them into the air with their breath.
Serra points – Term applied to loose amethyst crystals from southern Brazil.
Serra stone – Brazilian agate from the Serra do Mar.
set lever – The pivoted lever in a watch, one end fitting into the stem neck, the other working to shift the clutch lever into the hand setting position.
setting – 1. The part of a piece of jewelry into which a stone or other gem is directly set, with claws, bezel, or other means of clamping over the edge or girdle of the stone to hold it in place. See CHANNEL, FISHTAIL, TIFFANY, etc. 2. A metal ring holding the stone of a jeweled pivot-bearing of a timepiece, the outer side of the ring being fitted into a recess in the plate, bridge or cock of the timepiece and fastened therein by screws, or friction-tight; or in the case of a hole-jewel with end-stone, by being embraced between the endstone-setting and the bottom of the recess. 3. Stoppage of action of chronometer escapement, particularly in pocket chronometers, caused by a motion given by the wearer that may place the balance in a position where it cannot unlock the escapement by its own momentum. This is an inherent defect that prevents general adoption of this escapement for pocket watches, although it does not interfere with running of marine “box” chronometers, which are not liable to twisting motions, since they are used in relatively fixed position. See CHRONOMETER; JEWELING; JEWELRY FINDINGS. 4. Any part of the setting mechanism of a watch; lever, arbor, wheel, bridge, etc.
setting arbor – In many European and a few American watches, a steel pin that fits, with sliding friction, through a hole in the center-pinion, with the cannon-pinion drive-fitted on one end, and a square on the other end for key to set hands to time. Also called center-arbor, center-pin, or set-hands arbor.
setting bridge – A flat steel plate with spring arms which serves to position the setting parts of a watch and lock the setting lever in the setting position.
setting hammer – Hammer with head made of square steel, one end flat and the other beveled to a rather sharp edge, for reaching into corners of work.
shackle – A link for fastening parts together, as a watch chain and charm, so as to allow freedom to turn.
shaded pole – The split stators of A.C. clock motors with copper rings causing them to be slightly out of phase but also self-starting. See SELF-STARTING MOTOR.
shagreen – The dyed, burnished skin of reptiles or other animals used as ornamental covers for watch cases or jewelry.
shakes – In escapement adjusting, a “shake” is the play or amount of free motion of any part, between being at rest against one part and coming to rest on another part; like guard-shake, roller jewel shake, outside or inside shake of escape wheel teeth between pallets, etc.
shaking table – The agitated, inclined grease-covered surfaces over which the diamond concentrates are permitted to flow in the last stage of the separation at the African mines.
shallow – A condition in an escapement, or in gearing, in which the acting parts are too far apart; they do not engage deeply enough with each other to produce the correct action. A shallow escapement has insufficient depth of locking.
shank – 1. In a finger ring, the portion that surrounds the finger, exclusive of the head or box in which is set a gem, or which is enlarged to form a metal background for an engraved signet or ornament. 2. The part of a drill or tap by which the tool is held in a chuck or handle while in use.
shapes – Irregular rough diamond crystals, one of the five basic categories in the sorting of rough.
shaping – American term for bruting.
sharp-stuff – English trade-term for abrasive rouge of the coarser grains, used for smoothing work, preparatory to polishing it with finer-grained rouge or diamantine.
shears – A tool with two opposed blades used to cut metal. As handles are lengthened in relation to cutting blades, increased leverage permits cutting of heavier material.
shell – The slotted tubular part in cylinder escapement that forms body of balance staff and the lips of which act as pallets. See CYLINDER ESCAPEMENT.
shellac – A resinous substance exuded by an East Indian scale insect. Used as a low-melting, alcohol-soluble glue to secure pallet and roller jewels.
shell cameo – Cameo carved from the white layers of a shell, cutting down to the brown inner layers and leaving the figures in relief. Essentially a product of Florence, it seems to be almost exclusively an Italian art.
shell gold – An old method of making jewelry in which a very thin sheet of gold was stamped or beaten into a hollow form, stiffened by melting a coating of lead or soft solder to it inside, then having a “back” or “cover” or “other half” similarly prepared, soldered to it.
shepherd’s dial – A pocket-sized, cylindrical wood dial scaled with vertical markers for the months and time of day with an extending gnomon, which can be turned opposite the marked month and towards the sun while suspended to cause a shadow to fall on the cylinder denoting the time of day on a horizontal scale.
shield – In gem cutting, a variety of the emerald cut.
shifting-sleeve setting – In stem-set watches, mechanism in which a change from winding to setting is made by clutch-pinions on the stem-square, instead of by a rocking-bar device. See ROCKING-BAR.
shim – A thin piece of metal or plastic used to increase endshake or height of a watch part.
shipper – A lever in negative pendant setting mechanism, with a finger that engages a slot in clutch-pinion to shift the pinion from winding to setting position, and vice versa. See NEGATIVE SETTING.
shockproof watch – Term erroneously applied to watches having spring-controlled balance jewels. This term is outlawed by Federal Trade Commission regulations. See SHOCK-RESISTANT WATCH.
shock-resistant watch – A watch in which the balance jewels are mounted so that they have a slight spring-controlled movement under impact of pivots when the watch suffers a blow or falls; designed to prevent damage to jewels and pivots. Use of the term “shock-resistant” or “shock absorbing” is permitted if a watch possesses a level of resistance to damage from shock described in “Guides for the Watch Industry,” promulgated in 1968 by the Federal Trade Commission.
shoe – Horology. On watchmaker’s lathe, a metal block sliding on the ways of the bed, clamped in any position by a bolt and hand-nut, on which attachments are held, like handrest, sliderest, pivot polisher, etc.
short arc – Referring to the balance motion which is less than normal, usually occurring at the end of the mainspring’s run or in the vertical position.
shot bort – South African term for well-rounded diamond spheres with a radial structure, some translucence and a color from gray to rose or brown.
shot copper – Pure copper made up in small balls like shot/for alloying precious metals.
shoulder – 1. A surface from which something projects, like the flat face turned on a balance staff for the balance-arms center to be held against by the riveting. 2. Term often used loosely to mean a hub projecting from a shoulder, like “roller shoulder” for the lower part of a balance staff on which the roller table is driven. 3. Those parts of a ring that extend from the shank to the center of setting.
shoulder pivot – A form of pivot for arbors of watches and clocks, used in bearings without endstones, the endshake being limited at each bearing by contact of shoulder with plate or jewel. See CONICAL PIVOTS.
shovel – A trough-shaped hand-held lap used with a tailstock guide to polish cylindrical pivots.
shrouds – Metal discs on arbor of lantern pinion in which ends of rounds or pinion wires are supported. See LANTERN PINION.
shunt – A bypass for an electrical current, used in multimeters.
SI – Abbreviation used in diamond clarity grading for “slightly included,” “small inclusions,” or “slightly imperfect,” with sub-grades SIt and SI2.
Siam ruby – A term to distinguish the darker red rubies, with a touch of brown or orange, as distinct from Burma pure red to bluish-red. The dichroism shows a pronounced browner hue; they are far less fluorescent and they lack the rutile needle inclusions of the Burma stones, having instead thin drawn-out cavities, filled with liquid and round bubbles, and six-sided ruby (?) crystal inclusions. 2. Erroneous term for the dark red spinel found with rubies in Siam.
Siam zircon – The blue zircons especially, that are mined in Indo-China but largely shipped through Siam (Thailand), after heat treatment there.
Siberian amethyst – A term which has come to mean fine quality amethyst to the trade, but actually referred originally to an interesting variety of stone coming from Siberia, in which the color is situated at the point of the crystal, while the main body is colorless or only lightly colored. These are cut so that the color lies at the bottom of the stone, to which it gives a fine overall color.
Siberian aquamarine – Bluish green aquamarine from the Urals.
Siberian chrysolite – Misnomer for demantoid garnet.
Siberian ruby – Misnomer for red tourmaline.
Siberian tourmaline – Light carmine-red to violet tourmaline from the Urals
siberite – Violet-red tourmaline.
Sicilian amber – A genuine and highly-prized variety of amber darker in color than the amber of East Prussia, ranging from light wine red to reddish yellow and dark red. Commonly it is fluorescent, so that it has an oily greenish or bluish color; strongly fluorescent specimens are highly valued. Catania is the center of the amber-working industry; some German amber finds its way there.
side-cutting pliers – Pliers with cutting jaws set diagonally to the handles; differentiated from end-cutting pliers; which have cutting jaws set at a right-angle to the handles.
siderite – (sid’er-ite) An iron carbonate without gem value. However, the term has been applied to a blue silicified crocidolite or to a blue quartz, but is a most confusing and undesirable usage. Also, the technical description of an iron meteorite.
sideritis – Ancient term for a variety of diamond.
side-shake – Play or freedom of pivots to move sideways in their bearings, as in a “running-fit” or pivots in bearings. See END SHAKE.
sight – Euphemism employed by the Diamond Trading Company to describe the process by which a buyer is allowed to purchase a selection of rough diamonds that has been picked out for him by the De Beers affiliate in London. In recent times, 10 such sales have been held annually for some 220 invited customers (cutters and dealers). About 80% of the world’s gem diamond rough has entered commerce in this manner.
silica – (sill’ik-a) Silicon oxide; quartz is pure silica. Silica combined with other metallic oxides to form the silicates, a large mineral group which includes many gem stones.
silica glass – A natural glass like moldavite, but even richer in silica; has been found in the Libyan Desert, sometimes in large chunks which can be cut into pale yellowish-green stones. The refractive index is 1.462; specific gravity, 2.21; hardness, 6.
silicate – (sill’i-kate) A salt of one of the silicic acids in mineralogical terminology. Also applied to the glass used in imitation diamonds.
silicon carbide – A product of fusion of sand, coke, sawdust, etc., in electric furnace; crystals of it are broken and graded for use as abrasives, either as powders or mixed with binder and molded into grinding wheels, blocks, etc.; sold under various trade-names.
silicones – Polymers containing alternate oxygen and silicon atoms used with different organic forms as lubricants, rubber, glues, water repellents, gaskets, etc.
silicon gate – Transistor of silicon instead of ceramic or metallic oxide.
silk – Gemology. Inclusions, in the corundum gems, or rutile needles which give a flash of reflected light, resembling a fabric; hence the name.
silky luster – The luster shown by fibrous minerals, such as cat’s-eye and tiger-eye.
sillimanite – (sil’lee-man-ite) Named for Benjamin Silliman, an early American geologist. Also called fibrolite. It is one of the aluminum silicates (see also KYANITE and ANDALUS-ITE), crystallizing in the orthorhombic system, in prismatic crystals with a good cleavage and a fibrous appearance. Rare as a gem stone, it has only been found in a suitable condition in waterworn pebbles in Burma and Ceylon. It is strongly dichroic; hardness 7-1/2, specific gravity, 3.25, refractive index about 1.67. The fibrous structure of the usual type reduces its actual hardness to about 6-1/2 or so. Clear, pale blue facetable stones have been found in Burma, but the ready cleavage makes them very difficult to cut. The finest of all is a 35-carat gem in the Geological Museum (London). One to 5 carats is the normal range, but they are extremely rare.
silver – n. 1. A metallic element, used in jewelry, coinage, dentistry, photography, as an electroplate, and in many other applications. It is the whitest of metals, harder than gold, softer than copper, more malleable and ductile than any metal except gold, and probably the best conductor of heat and electricity. Melting point 960.5°C.; specific gravity 10.5; chemical symbol Ag. It is classed with the precious metals because its properties make it desirable for coinage and jewelry, and with the noble metals because of its resistance to oxidation. For most industrial purposes it is hardened by the addition of some other metal. Sterling silver contains 925 parts fine silver with 75 parts some other metal, usually copper. Coin silver, used in early 19th Century pieces, was an alloy of 900 parts silver to 100 parts copper, the same proportion that was used for U.S. silver coins. Other silver alloys used in Europe may be marked to indicate their fineness, e.g., 800, 830, 875. The multi-nation Confederation Internationale de la Bijouterie, Joaillerie, Orfevrerie, des Diamants, Perles et Pierres has recommended two fineness standards: 925 and 800 parts per thousand. Molten silver can absorb up to 22 times its volume of oxygen, which is given out on cooling, to cause the so-called spitting of silver. Silver is attacked by hot nitric or hot sulphuric acid; scarcely at all by hydrochloric acid or by aqua regia. It is quickly attacked and darkened by sulphur and its compounds. 2. Tableware made of, or electroplated with, silver, such as knives, forks and spoons. 3. Silver coin.
silver – v. To coat with silver, as by electroplating, or with a film of silver salt.
silver cape – A color grade in diamond classification, the group following the blue whites and white.
silver deposit – A term used to describe a decoration, especially on glassware, where the silver has been electro-deposited.
silver filled – A plating by soldering, brazing, welding or other mechanical means of a silver alloy of not less than .925 fineness, when the plating constitutes at least 1/20th of the metal in the entire article; a bi-metal or tri-metal introduced in 1974 for jewelry. The voluntary standards were based on those which had long been in effect for gold filled. Synonym: Silver overlay.
Silver Peak jade – A term used in Reno, Nev., for malachite.
Silver plate – An article made from base metal electroplated with pure, i.e. fine, silver. Base metal may be nickel silver, copper or brass.
silver solder – An alloy of silver, copper, and zinc.
silver steel – A British term for drill rod.
Simav stone – Fire opal, from the vicinity of Simav, in Asia Minor. It occurs in yellow and brown hues in masses up to a walnut in size in a quartz porphyry, associated with common opal and tridymite. The occurrence has been known since the Middle Ages and the stones were in some demand. Erroneously known as Simon and Simao stone.
simetite – Sicilian amber, from the Simeto River, a principal source. See SICILIAN AMBER.
simili – Lead glass diamond imitations, often with high dispersion through the addition of thallium salts.
simulated stones – Imitation manufactured gems.
single bevel – A simple style for cutting any opaque stone, such as onyx, carnelian, etc., with the sides beveled from flat top to flat base.
single cut – 1. Gemology. A primitive form of brilliant cutting, fashioned from the rough octahedron by truncating the corners and placing a table and culet on the stone, 18 facets in all. It preceded the modern brilliant and is still in use on small stones of low quality. See DOUBLE CUT, TRIPLE CUT. 2. Horology. Variety of files with teeth presenting a continuous cutting edge slanting from side to side of the file, used for smoothing work; differentiated from double-cut files in which the continuous cutting edges first made in manufacturing files are given a second series of cuts across that produce pointed teeth.
single-beat escapement – Class of escapements in which impulse is given to balance at every other beat, like chronometer and duplex escapement. See COUP PERDU.
single refraction – A term used in distinction from double refraction; by which is meant that the transmitted ray is not broken up, but passes through the crystal with all its vibrations at the same speed, since all directions are alike to it. Crystals in the isometric system and amorphous materials, like most liquids and unstrained glasses, are singly refracting.
single roller – Type of lever escapement in which there is one roller table to perform both the impulse and safety-action functions. See LEVER ESCAPEMENT.
sinking tool – See COUNTERSINK.
sinople, sinopal – A variety of aventurine quartz, with scaly inclusions of red hematite.
Sioux Falls jasper – A fine brown jasper found in large quantities in a quarry at Sioux Falls, South Dakota, and used for large ornamental objects.
six face – A Holland rose diamond with but six faces, a simple pyramid.
six-prong setting – See PRONG SETTING.
sixteen corner – A brilliant-type of cut, with 34 facets. Used on small and poor stones, like the single cut.
sizes – 1. Diamond. In sorting rough diamond crystals, those weighing one carat or more. Smaller crystals are termed melee. In referring to polished diamonds, those weighing a fifth of a carat (0.20 ct.) or more; smaller polished diamonds are termed melee. 2. Ring. See RING SIZES. 3. Watch. See WATCH SIZES.
sizing – Altering the diameter of a ring to fit a finger, either by cutting out a portion of the circlet and soldering the cut ends together to make the ring smaller; or by cutting the circlet and fitting in a length of metal of same cross-section as the ring, and soldering both joints into the ring, to make it larger. With modern sizing equipment, rings may be enlarged or reduced by pressure, rolling and butt welding.
skeleton – Horology. 1. Design of plates, bridges, etc., in a watch or clock, cut into open spaces to show all the wheels, escapement, etc. 2. Hands for watch or clock, cut out except the outlines, filled in with luminous material for use with luminous dials.
skief – Horizontal cast iron wheel used in diamond polishing, 10-12″ in diameter, 1″ thick, mounted on a vertical spindle; spinning at 2500 revolutions per minute. Also spelled “skaif” and “scaife.”
skylight – Design of watch case, open face, but with very broad bezel and relatively small glass.
skystone – Benitoite.
slabbing – First step in making watch jewels from natural stone or synthetic stone boules; comprises sawing the lump into thin slices, which are next cut into small square bits, one for each jewel to be made by further turning, drilling and lapping operations.
slaked lime – Calcium hydroxide, used as a cement.
slate borax – Borax made up into hard cakes, for rubbing with water on a slate block, for preparing flux for hard-soldering jewelry, etc.
slaves’ diamonds – Portuguese misnomer for colorless topaz.
sleeper – Small, plain earring worn to keep ear perforation open.
sleeve – In the pendant of case of a watch having negative-setting work, a split steel tubular spring with interior projections engaging a slot in the stem, to hold the stem in positions either for winding or setting the watch. See POSITIVE SETTING.
sleeve wrench – Set of steel tubes with ribs on outside, to engage slots in the sleeve in case of pendant-set watch, for adjusting position of sleeve.
slide – 1. Horology. In a lever escapement, the movement of a pallet stone from the instant when it first locks an escape wheel tooth, until the stone can move no farther due to the lever coming to rest against a banking. See DRAW. 2. Jewelry. A cork-filled ornament which slides on a long neck chain which it adjusts to desired length.
slide gauge – Instrument for measuring lengths, with graduated bar on an end of which is a fixed jaw, with another jaw movable on the bar and having on it a vernier scale for subdividing the units on the bar. See BOLEY GAUGE; VERNIER.
slide-rest – An attachment for the watchmaker’s lathe; a base bolted to lathe bed, with a gibbed slide on it, turnable to any angular position, and on this another slide on which is an adjustable tool-post for holding turning tools. Each slide has a leadscrew and crank-handle to move the cutting tool in doing cylindrical or taper turning, facing, etc. Some slide-rests have a third slide for doing square-shoulder work, or mounting other attachments, like wheel-cutting attachments, rounding-up tools, grinders, pivot polisher, etc. In turning, a slide-rest offers two advantages over hand-tools; the leverage of the crank-handle and screw multiplies power of the fingers and saves fatigue in doing much of heavy work; and the guiding action of the slides gives exact control of cutting-tool in producing rectilinear faces on the work.
slide rule watch – A watch with outer movable ring marked with a vernier-type scale and compared with a correspondingly marked frame upon which it can be turned for mathematical calculations.
sliding carrier – A ferrule on a Jacot lathe whose position is adjustable.
sliding fit – In mechanism, a fitting of two parts to work together so that one can be moved in the other, as of the spindle in a lathe tailstock. See DRIVING FIT; RUNNING FIT.
sliding friction – A kind of friction such as occurs in the action of escape-wheel teeth on pallets; of pivots in their bearings; of mainspring coils on each other, etc., contrasted principally with ROLLING FRICTION.
sliding tongs – A small hand-vise or pin-vise in which the jaws are closed by moving a ring along tapered bars between jaws and handle. See PIN TONGS.
slightly imperfect – See SLIGHTLY INCLUDED.
slightly included – A diamond clarity grade between very slightly included and imperfect in the flawless-to-imperfect range. Internal characteristics and finish faults are readily seen by a trained eye under 10X magnification, although invisible face-up to the unaided eye. The term, slightly included, is preferred to the older expression, slightly imperfect. Sub-grades SI1 and SI2 are used, according to the number, location and type of blemishes.
slip – A small hand-lap made of metal or stone, for grinding or polishing pivots or other lathe work.
slitting wheel – Bronze diamond saw for gem sawing.
slopes – The impulse-faces of teeth of escape wheel in a cylinder escapement; also called inclines, or lifts.
slot – 1. The notch in the fork of a lever escapement, in which the roller jewel works during unlocking and impulse. 2. The opening in the shell of cylinder in cylinder escapement, through which escape wheel teeth pass. 3. The groove cut lengthwise in balance staff of duplex escapement, through which the locking-teeth of escape wheel pass at each beat. 4. The neck in a stem in which the set lever pin is positioned.
slow train – Gearing for a watch train calculated so that the balance will make less than 18,000 beats per hour. See ODD-BEAT; TRAIN; QUICK TRAIN.
slug pearl – Grape-like clusters of intergrown freshwater pearls.
slush box – The box beneath and around the lap in which the “mud” from the polishing operation is preserved.
slush metal – A low-fusing alloy used for inexpensive hollow castings. See WHITE METAL.
smaragdite – A bright green amphibole, near actinolite in composition. It makes a compact mass of green fibers and has been used as a decorative stone. An interesting and attractive occurrence is one in North Carolina, where red corundum, rubies, have formed in a matrix of smaragdite. A variety has been sold as jade, in China. See GOODLETITE.
smaragdolin – Wrongly called synthetic emerald or reconstructed emerald: A beryllium glass with the composition of emerald, green in color; refractive index, 1.62; hardness, 5-5.5; specific gravity, 3.3-3.45.
smaragdus medicus – Malachite.
smithsonite – A zinc carbonate; sometimes, when abundant, an ore of zinc; when pure it is white, and rarely in good crystals. However, it is often tinted by impurities of copper, which color it pale blue, or cadmium, which makes it yellow. These pieces are attractive and are used locally as cabochon gemstones, especially in the Southwest, where it occurs most commonly. Strongly double refractive 1.62 and 1.85; specific gravity, 4.3 to 4.45;hardness, 5. See AZTEC STONE, BONAMITE, CALAMITE.
smoky opal – A smoky brown variety of common opal.
smoky quartz – A common variety of crystallized quartz, with a smoky brown cast, varying from quite light to very dark, when it is called morion. True cairngorm is a smoky quartz; darker shades go under the latter name. Much citrine is derived from smoky-quartz by a heating process which drives off the smoky cast, leaving a fine yellow to orange brown hue. It is characteristic of igneous rocks and solutions; pegmatite dikes, the Swiss crystal cavities, etc.
smoky topaz – Misnomer for smoky quartz.
smoky stones – Diamonds with a smoky tinge, either through the stone or in the corners, in which latter case they are known as glassies with smoky corners. They usually have a good luster and crystal form, but are easily split.
snail – In striking clocks and watches a cam that rotates with the time train and has a circumference of spiral form, divided into “steps” on which a lever falls hourly, etc., controlling the number of strokes.
snailed hook – Type of fastening for inner end of mainspring, in which the hook is formed by milling out one side of barrel arbor eccentrically, leaving the hook standing; this to avoid malformation of the spring-end when the mainspring is fully wound up.
snailing – Giving wheels, circular caps, etc., a grained finish consisting of slightly curved lines radiating from the center; by using an abrasive lap on a rotary pivot-polisher or traverse grinder, applying one corner of the lap to the work, to avoid grinding in opposing curves.
snake chain – Chain of round, square, rectangular or oval cross-section, automatically produced by machine. The joints between the links are so curved as to suggest snakeskin.
snake-skin agate – A nodular gray brown chalcedony from Oregon which weathers and then is tumble polished, to reveal a reticulated surface pattern resembling snake skin. The odd shapes are often fashioned into imaginative hand-crafted jewelry by the amateurs.
snap – 1. Horology. The exposed catch on locking-spring of a hunting watch case. 2. Jewelry. A locking device used on bracelets and some necklaces.
snap-on dial – Watch dial fastened to lower plate by a ring of thin metal surrounding edge of dial and pressed or sprung over recessed edge of plate.
snap-stem – grooved, spring-end stem that snaps together with its male or female counterpart, used in watch cases that do not open at the back.
snarling iron – metal bar that is turned down at one end, which is secured in a vise and turned up at the other end. The upward end is inserted inside of a hollow article such as a pitcher and blows with a hammer are struck on the iron near the vise. The other end rebounds and serves to raise or “boss” out the design on the piece of hollow ware. This process is one form of repousse.
snips – small hand shears used to cut metal. See SHEARS.
soaking – In heating steel for hardening, keeping it a short while at the heat chosen for quenching, to assure uniformity of heat throughout the piece before it is quenched. See HARDENING; STEEL.
soapstone – Steatite, but generally a massive variety, slightly harder because of impurities, and widely used in sinks, table tops, etc.
Sobrisky opal – Opal from Death Valley, Calif.
sodalite – A mineral of the lapis lazuli group, with hauynite and noselite. It often occurs pure in silica-poor rocks and sometimes has a violetish blue color which makes it suitable for use as a substitute for lapis lazuli in decorative objects. It is never transparent, and generally is variable in color. Refractive index, 1.49; hardness, 5.5-6; specific gravity, 2.14-2.30. Common and mined in Africa, Brazil and Canada.
sodium hydroxide – Strong alkali. Hot solution used to dissolve shellac from some mounted work. Will dissolve aluminum.
soft-soldering – Soldering metal pieces together with any solder that melts at a relatively low degree of heat; at less than a red heat. See HARD SOLDERING.
solar cell – A Space-Age energy source used in timepieces, which employs photons on layers of silicon to produce photovoltaic action that energizes the timepiece.
solar-powered watch – An electrically-driven watch the power of which is replenished by light-sensitive cells that convert light into electrical energy.
solder dispenser – Electrically operated machine that automatically dispenses desired amount of paste solder through a controlled hypodermic type dispenser. See SOLDER PASTE.
soldering – (sod’er-ing) Uniting pieces of metal by melting between them another kind of metal. See HARD SOLDERING; SOFT SOLDERING; SOLDERS.
soldering block – Block of charcoal, asbestos or other refractory material on which soldering is done.
soldering clamps – Adjustable device for holding together pieces to be joined by soldering.
soldering fluid – A liquid of muriatic acid used as a precoating for soft soldering.
soldering machine – An electric device for soldering metals. Adjustable for varying thicknesses of metal and varying temperatures.
soldering tweezers – Tweezers for holding work of any kind while heating it, for soldering, hardening, etc., usually having jaws that may be clamped on work.
soldering wig – Flattened coil or mop made of iron binding wire on which soldering is done. The open spaces between the wires aid in the even distribution of heat beneath the work.
solder paste – Granulated solder in paste form, prepared with flux; comes in soft, silver and gold solders. See SOLDER DISPENSER.
solder preforms – Solder, precut to shapes and sizes to fit specific soldering jobs. Used generally in hydrogen furnace.
solders – Metal alloys prepared for use in soldering. A general classification is into soft solders and hard solders. Soft solders are mainly alloys of lead and tin; these with bismuth added melt at the lowest heat; lead and tin in equal parts (the commonest soft solder) or with more lead than tin, melt at highest heat for soft solder. Hard solders are alloys of gold, silver, or brass, and melt when the work is brought to a red heat; and make the strongest joint. See SOLDERING. Platinum solders are alloys of platinum, palladium and fine gold.
soldier’s stone – Amethyst.
sole – Any of the thin, flat steel parts in watches for support of clicks, springs, etc.
solenoid – A coil of insulated wire wound on a tube to form a hollow coil; this with an alternating current of electricity flowing through it makes a demagnetizer for watches, tools, etc., when these are passed through the solenoid.
solid banking – The banking of a pallet fork against a part of the movement instead of banking pins.
solid gold – A term that some would reserve for fine or 24 karat gold for the reason that an admixture of copper, silver or other elements results in a metal that is not solidly, or purely, gold. However, in an advisory opinion dated June 13, 1967, the Federal Trade Commission held that “solid gold” may be used to describe articles that do not have a hollow center and that have a fineness of 10 karat or more.
solid state timepieces – A timepiece without moving parts. Such watches and some such clocks draw energy from a battery; other such clocks from a wall outlet. The power energizes a quartz crystal or other frequency standard, the vibrations of which are reduced by an electronic circuit; the time is shown by digital display.
solitaire – French word meaning “alone,” applied in jewelry—especially finger rings—to the mounting of a single diamond or other stone. Many engagement rings are thus mounted; the ring itself is also called a solitaire.
sonic watch – Watches with vibrating reeds or tuning forks.
Soochow jade – Misnomer for soapstone, so named from an occurrence in Soochow, China.
soudee emerald – (soo-day) From the French emeraude soudee, “soldered emerald”; a crown and base of rock crystal joined by green cement to resemble emerald. Soudee sur spinelle substitutes synthetic spinel for rock crystal.
sourdine – A pin through the edge of the case of a striking watch, which can be pressed in by a finger to silence the gong, and then the hammer strokes are felt by the finger instead of being heard.
South African jade – Misnomer for a compact fine-grained green variety of grossular garnet from Buffelsfontein, Transvaal. Associated with black chromite, it often contains bands of that material, and it is used in decorative objects like ashtrays, small boxes, etc.
South Sea pearl – Trade terminology for pearls from Tahitian and other South Sea waters. Cultured pearls grown there, particularly on the northwest coast of Australia, are considerably larger than the Japanese cultured pearls and are grown in the large Margaritifera oyster.
spade hand – Watch or clock hand with pointer formed like a spade on a playing-card.
spandrels – Corners of a square clock-dial that are outside the numeral-circle; or any ornaments placed in such corners.
Spanish citrine – Citrine from Spain.
Spanish emerald – Fine quality emerald; an old term of no validity today since no emerald has been found in Spain and presumably refers to the Colombian gems shipped to Spain at the time of the Conquest. Also applied in the trade to green glass imitations.
Spanish lazulite – Cordierite.
Spanish topaz – Misnomer for citrine; see MADEIRA TOPAZ.
spar, spar ornaments – Decorative objects made of fluorspar; spar in common usage is an transparent, cleavable, crystalline material with a high luster; calc spar, fluor spar, heavy spar, etc.
Sparex – Trade name for a granular pickling compound without fumes or hazards of acid. See PICKLE.
spark suppressor – Diodes, resistors in electric watches which diminish the erosion due to sparking contacts.
spat – Young, free-swimming oysters when they are first released from the body of the parent.
spatula – A knifelike instrument with various blades used in shaping, fashioning and repairing wax patterns. Manual spatulas are heated in a Bunsen burner while electric spatulas have built in heating elements. Larger spatulas are used in mixing investment.
specific gravity – A property of any substance, its weight in relation to an equal volume of distilled water at 4°C; abbreviated to S. G. It is one of the most important properties to aid in the determination of a gem.
specimen – Gemology. A stone of unusual quality, a unique piece.
spectroscope – An instrument used in gem identification; it spreads light entering through a slit at one end into the visible light spectrum, enabling the tester to determine which, if any, segments have been absorbed by the gemstone through which the white light has passed. Not all gemstones show a characteristic spectrum; but it is helpful in distinguishing, for example, yellow, green and blue sapphires from their synthetic counterparts, and dyed green jade from naturally colored green.
spectrum – The sequence of hues observed when white light is separated into its components, as in a rainbow or by a prism.
spectrolite – Gem name applied to the blacker and more brilliant Finnish labradorite.
spectrometer – An instrument for measuring the intensity of the various parts of the spectrum.
spectral colors – The pure hues of the dispersed spectrum.
specular hematite, specular iron – Black brilliant hematite, often engraved into an intaglio and used in signet rings. It gives a red streak on a streak plate and can thus be told from an imitation with a pressed image, even when very similar in appearance. Hematite is the most important ore of iron, but is most commonly soft and red, rather than hard and black. Specific gravity, 4.95-5.16; hardness, 6%.
sperm oil – A lubricating liquid, chemically a liquid wax, derived from the blubber in the head of the sperm whale. The better grades of sperm oil, especially resistant to evaporation, were used for lubricating watchmakers’ and jewelers’ lathes and for use on oil-stones.
spessartine – (spess’ar-teen) A manganese aluminum garnet of a brownish-red to orange–brown or yellow-brown hue. Refractive index, 1.79-1.81; specific gravity, 4.12-4.20; hardness, 7%. Uncommon and very rare in gems of any size, which is the only reason they are not in wider use and better known. Sometimes found in the gem gravels of Ceylon, 6 and 12 carat stones are considered exceptional. Flawed but well-colored stones of some size were found at Amelia Courthouse, Va.
sphaerolite – (sfair’o-lite) A nephrite texture, sometimes observed under the microscope, of fine radiating spheres of slender needles.
sphaerulite – A term which has been used for an obsidian with small included spheres of radiating crystallites.
sphalerite – (sfal’er-ite) Sulphide of zinc, the principal ore of that metal. It sometimes occurs in transparent gemmy yellow isometric crystals, is very heavy (specific gravity, 4) and has a high refractive index (2.37). Specimens from Spain have been cut as a gem; when well cut and polished it resembles a canary diamond; but it is too soft and too cleavable to have any real gem value. Its color ranges from white through yellows, reds, greens, browns to black.
sphene – (sfeen). A now widely used synonym for titanite, calcium titanium silicate, and, for a time, the internationally approved name for this mineral. Mineralogists have now reverted to titanite, which seemed, in spite of the accord, to have had better acceptance. It is a common mineral in some plutonic rocks, in which it forms small brown crystals. It is also found in metamorphic rocks and in pegmatites. Outstanding examples for cutting have turned up in Mexico (Baja California) and in Minas Gerais, Brazil. Earlier it was known in large gemmy crystals only from the Alps and was long so rare that its gemstones were highly regarded and costly, even though their low hardness militated against general jewelry use. It has strong dispersion and makes a fiery gem. Colors are yellow, golden brown and emerald green, the hardness is about 5 to 5l/2, the strong refraction is double, 1.90 and 2.03. The natural approximation, though strongly tinted, of some of the titania-bearing synthetics imitating diamonds. It is popular with collectors and true connoisseurs. Large stones are still rare and costly, though they are commoner than when their only source was Alpine.
spherical hairspring – Form of balance spring in which the coils not only increase in diameter gradually from each terminal, but approach each other from above and below, the spring thus approximating the shape of a sphere.
spike drum – In a clock wound by pulling a chain, the grooved pulley on main wheel, with pins set in groove to engage links of chain.
spinach jade – Nephrite.
spindle – A long, slender shaft upon which a wheel or pulley may turn.
spinel – (spin-ell’) An important gem mineral, a magnesium aluminate. It crystallizes in the isometric system, usually in octahedrons, and is often twinned into flattened triangular plates. This type of twinning is common in diamonds (macles) and is known as spinel twinning. It is hard (8), heavy (3.5 to 4.1) and fairly high in its refractive index (1.72). Red is a common color (see BALAS RUBY); it is also green, blue, brown, violet and black. Its properties vary considerably with the composition and color. A fine gem stone, but overshadowed by the corundum gems with which it is commonly associated. Ceylonite, pleonaste, rubicelle, chlorospinel, almandine-spinel, picotite, gahnite and spinel-ruby are all names which have been given to this mineral. It is a common synthetic stone, taking light blue and other colorations unlike the synthetic corundum (“synthetic aquamarine” or “synthetic zircons” are often synthetic spinel) but contains a higher proportion of alumina than the natural stone. The synthetic gems have anomalous double refraction, and a refractive index of 1.73.
spinning – One of the most common methods employed in the manufacture of metal ware, including silver hollow ware. It is done on a high-speed lathe. A disk of metal is placed against a wooden chuck or mould and both are revolved at high speed. The workman with a simple tool, which he guides on the lathe rest, causes the metal to form over the chuck, thus producing a vessel of like shape; this process is used in making bodies of tea and coffee pots, bowls and the like.
spinthariscope – A small instrument constructed by Sir William Crookes for the observation of fluorescence of a powdered substance under radium emanations.
spinthere – (spin-thair1) A greenish sphene.
spiral – 1. A plane curve traced by a point that moves around a fixed center and continually increases its distance from the center. 2. French for hairspring of any form. See HELIX.
spiral bracelet – Bracelet formed of two or more wires, chains or strands of pearls to form a spiral effect.
spiral fluting – Fluted work which suggests continuity of pattern by arranging the flutes as spiral.
spirit lamp – A lamp with wick using alcohol.
spirit level – The liquid-encased level-bubble indicator in a balance poising tool.
spit-stick – A graver of knife-edge form, specially prepared for bright-cutting settings. The top of the graver is ground down to half its original height; the sides are slightly rounded, then highly polished on 4/0 emery paper, or on a boxwood lap with fine diamond powder.
splinter – Thin slivers of diamond, less than a carat in weight, splints.
split brilliant – A name which has been applied to brilliants (diamonds) cut from a perfect octahedron by sawing it in two at the center. Also, a modified, 42-facet brilliant, a cutting perhaps used on some small stones.
split chuck – Self-centering “wire” chuck of American type watchmaker’s lathe.
split facets – Another term for the half, cross, skew or skill facets.
split lap – A wood or felt lap with saw cuts radiating from center. See VISIBLE LAP.
split-ring – An item of jewelry findings, for attaching objects to be worn on chains, etc., resembling a plain ring but split horizontally so another ring or link may be connected with it by separating the split halves and turning them until they meet again with the link inside the split ring.
split-seconds – Chronograph or timer watch with two sweep-seconds hands that can be operated in turn to time two successive happenings, as the finish of the first and second horses in a race.
split stones – A diamond classification term, the synonym for cleavage.
spodumene – (spod’u-meen) A lithium aluminum silicate, found in complex, lithium-bearing pegmatite dikes, associated with rubellite, topaz, beryl, etc. First found in gemmy crystals, lilac to pink in color, at Pala, California, and named kunzite. Subsequently found in Madagascar, Brazil and Afghanistan. A rich green, chromium pigmented variety is known as hiddenite. Other colors include yellow, pale green, and white. It crystallizes in slender crystals in the monoclinic system, has a good prismatic cleavage and has its best color along the vertical axis. Careful cutting, with the table at right angles to this axis is essential for the best results. Its hardness is 6 to 7; specific gravity, 3.3 to 3.20; and refractive index, about 1.67.
sport watch – Anglo-Swiss term for chronograph or timer watch with start-stop-and-flyback sweep second hands, used for timing athletic contests, etc.
spotted stones – A mine classification of diamonds; crystals containing spots which must be removed.
spread – The width of a stone at the girdle.
spread brilliant – A diamond the width of which is excessive, in relation to the depth.
spreading-tool – A special punch-and-die tool for enlarging the diameter of gear wheels.
spring bar – The spring lug in a wrist watch case used to position the bracelet. See LUG; SPRING PIN.
spring-detent – Type of detent in a chronometer escapement; in which the locking and unlocking movements are under control of a thin flat steel spring that is part of the detent; differentiated from the “pivoted detent,” which turns on a pivoted arbor on which is a small spiral spring that controls its movements.
spring-drive – Class of clocks in which motive power is provided by winding a mainspring, differentiated from weight-driven clocks.
spring gauge – Spring-operated gauge used in measuring thicknesses in douziemes or millimeters. See DOUZIEME.
springing – The work of the specialist who fits and adjusts watch balance springs.
spring-pin – A hollow rod, with plunger at each end, normally pressed outward by a coiled spring inside the tube, to form pivots engaging in holes in lugs on a wrist-watch case, forming with the lugs a bail to attach strap or similar part of bracelet to the case.
spring ring – An item of jewelry findings, for attaching charms, medals, etc., to be worn on chains; comprising a circular tube enclosing a coiled spring that presses on the inner end of a curved wire partially projecting from the tube to complete its circle, which may be opened by pressing on a small finger-piece on the wire.
spring tweezers – Tool for holding work, usually hot. They differ from standard tweezers in that they open when the sides are squeezed. See SOLDERING TWEEZERS.
sprue – Portion of a casting formed by the entering metal flowing through the gate or channel of mold.
sprue former – Device used to form entry gate in investment mold.
sprung-over – Arrangement in designing watches in which the hairspring lies above the balance arms; differentiated from sprung-under watches with hairsprings located under the balance arms.
square – 1. Part of any arbor in a timepiece to which a key is applied to turn the arbor, as in winding or setting, 2. A metal instrument with one bar at a right angle to another, for testing squareness of work. 3. Part of winding stem on which clutch or bevel pinions fit in square holes.
square cut – A fancy diamond shape, a square stone. Also used on large size stones of various sorts, if the rough is so shaped that the best recovery will be made with such a stone.
square cut brilliant – A 34-facet brilliant stone developed from the 18-facet single cut by truncating each of its edges with a double-cut facet.
square hook – Form of fastening of outer end of mainspring to inside of barrel that is of advantage for use in marine chronometers. It comprises a rectangular block of steel riveted to the spring and fitting and engaging angularly in a rectangular hole in the barrel wall.
square hexagon – A gem shape, a regular six-sided figure, in distinction from the slender pointed hexagon and the oblong blunt hexagon.
square prong – A high four-prong setting with 90 degree angles at the four corners, usually having heavy post formed by a dovetail or similar piercing along the flat side.
square shape – A form in which gemstones are cut, with step facets.
S.S. – Abbreviation sometimes used for sterling silver.
stackfreed – A device for equalizing motive power in a timepiece, used in south Germany during the 16th Century. A roller on a short spring applied pressure to a cam on the mainspring arbor shaped so that the fully wound spring’s power was opposed by the stackfreed spring power, and gradually, vice-versa, the stack-freed adding to the mainspring power after the latter was about half run down. See FUZEE.
staff – A pivoted shaft, or arbor; but specifically the arbor on which is mounted the balance of a watch or other timepiece.
stained agate – Agate which has been artificially colored, either by soaking in aniline dyes or in some other solution which brings about a coloration which makes the banding more pronounced. The so-called Swiss lapis is another stained stone, as are the blue, green and black chalcedonies.
stainless steel – Steel containing chromium, which is comparatively non-oxidizable; used for watch cases, cutlery, etc.; not used for watch and clock parts nor springs, because not hardenable by heating and quenching. See STEEL.
stake – 1. Block of metal with holes in it of various sizes, used on bench for supporting work during punching operations. 2. Small anvils, held in bench vise, for various special purposes in horology, jewelry and watch-case work.
staking tool or set – A set of punches for various uses in horology, with a stand to support punches vertically over a die-plate with holes of assorted sizes, and a set of stumps to augment the die-plate; mainly used for riveting work.
stamping – 1. Producing quantities of similar pieces of work by striking the material into form in dies in power-driven presses; or, in some smaller jewelry shops, in foot-operated die presses. 2. Impressing lettering or decorations on leather, with heated metal die or type, with or without gold-leaf in the imprint. 3. Marking articles made of precious metals, to indicate quality of metal and registered trademark. See HALL MARKS.
standard plate – An electrodeposit equivalent to 2 Troy ounces of silver per gross of teaspoons, resulting in an average thickness of 300/1,000,000 or 3/10 mil. Also termed single plate oral.
stantienite – A black fossil resin, known as black amber. Name derived from Stantien, of Stantien & Becker, a pioneer firm in the mining of amber in East Prussia, when the industry was first placed on an organized basis.
star – In gem terminology, a rayed figure with any number of arms, most commonly 4 or 6, seen in cabochon-cut translucent stones. See STAR SAPPHIRE, etc.
star agate – A variety of agate with star-shaped figures.
star cut – 1. A diamond shape introduced in Europe in 1974, consisting, in effect, of a round brilliant from which project five, six or eight “rays;” offered in a weight range of 30 pts. to 2.5 cts. 2. A complicated brilliant form of cutting with 154 facets used on colored stones.
star facets – The eight small three-sided facets flanking the table in a brilliant. A star facet extends half-way across the original junction of a main top facet (one of the four corner or four bezel facets) with the table, and half-way down the junction of a corner facet and a bezel facet. See BRILLIANT.
star lever – In a chronograph watch mechanism, the arm that transfers power from crown-and-stem to the pawl that operates the star wheel for starting the sweep-seconds hand from zero.
starlite – A fanciful name coined by Dr. G. F. Kunz for the blued zircons of Thailand.
starolite – A confusing trade name for an asteriated pale rose quartz with a colored back, in imitation of a star sapphire or ruby.
star ruby – A cabochon-cut ruby which shows a six-rayed star when illuminated by a point source of light. It is caused by innumerable parallel tubes or rod-like inclusions, oriented parallel to the six sides of the original crystals. Reflections from the sides of these inclusions cause the light streaks which make the arms of the star.
star sapphire – A blue to gray or fancy-colored stone showing asterism like that described above. Just as transparent sapphires may come in any color, so may star sapphires; though fine fancy hues in this class of stone seem to be rare.
star stone – Any gem showing asterism. Also applied to a petrified wood with clear portions through which the gold backing may be seen, recalling a star-flecked sky; an old German term, little used today.
star wheel – Any of the star-shaped, pointed-toothed wheels in a calendar and/or striking timepiece, used to suddenly index a new date or hour division, as in striking.
static poise – The condition a watch balance is in after it has been poised, and as tested on a poising tool; differentiated from the conditions under which a balance runs in a watch when it is subject to action of centrifugal force. See DYNAMIC POISE.
stator – In the motor of an electric clock, the field-part that does not move; differentiated from the rotor, which including its shaft does move in the running of the motor. See ELECTRIC CLOCKS; ROTOR.
staurolite – (stor’o-lite) A brown hydrous iron aluminum silicate, rarely found in crystals with any clarity. It crystallizes in the ortho-rhombic system, frequently in intergrown twins which make a perfect cross. Its principal use is as a good luck charm in this form. See FAIRY STONE; CROSS STONE. Hardness, 7-7Vi; specific gravity, 3.4-3.8; refractive index, 1.74. Many of the crosses sold as jewelry pieces have had the surfaces ground down; they are no longer in quite the shape in which they were first found. Some imitations have also been seen on the market; they are far softer than the genuine material and can easily be distinguished with a knife.
steady pins – Short metal pins for determining the position of a part held fast to another part by a screw; for example, the steady pins in the base of a balance cock fit closely into holes in the movement plate, preventing side-play; the screw then only need hold the parts together; it could not by itself assure exact oppositeness of the two sets of balance jewels when the watch is reassembled each time, but the steady pins do that.
steady-rest – A lathe attachment, adjustably bolted to bed, with metal fingers to set against a very long piece of work in the lathe, to prevent its bending or buckling under pressure of the cutting tool.
stealite – Chiastolite.
steam generator – Machine that produces steam which is used, under pressure, to clean and remove polishing compounds and dirt from jewelry. Used also to remove investment from castings.
steatite – Soapstone, an impure talc, used in carvings, but often ambiguous and includes such material as saussurite and agalmatolite.
steel – A hard, tough metal, composed of iron alloyed with small amounts of carbon and sometimes other metals.
steeple cup – Horology. Shaft in a timepiece which connects crown to winding pinion and setting mechanism.
stem bridge strap – A steel spring, in some high-grade European watches with push-piece setting, that holds the stem in place in use.
stem-wind – Class of watches in which the mainspring is wound by turning a crown on the stem, which passes through the pendant of the case; in England called “keyless;” differentiated from key-wind watches in which a detachable key is applied to a square on barrel-arbor to wind them.
step- One of the shouldered faces on a snail in striking work, on which a pin or finger falls to govern the number of strokes on bell or gong.
step-chuck – 1. A chuck for watchmakers’ lathe, with a shallow recess on the face around the hole; otherwise the same as ordinary split or wire-chuck; for holding jewel settings while turning, burnishing, etc. See STEPPING DEVICE. 2. One of a set of chucks with shouldered recesses to hold wheels or discs in watchmakers’ lathe; also called WHEEL CHUCK.
step cut – A type of cutting widely used on colored gems, with long parallel facets, called steps, arranged parallel to the girdle. The number of facets on the bottom is indeterminate, on the crown there are usually two or three rows. On the pavilion, elongated stones commonly have an extra pair of facets on the sides. The corners are frequently truncated by a single facet which is, in turn, cut off by the second row of large facets. A more octagonal stone will usually have the complete series of corner facets, in place of the single one of the elongated stones.
Stephen’s stone – A spotted agate, small red spots evenly distributed over a white or gray ground mass, giving the whole a rosy tone.
stepping device – An accessory to the watchmakers’ lathe, with which ordinary split chucks can be used in place of special jeweling chucks. A plunger passing through the lathe spindle holds a flat-faced plug inside the chuck hole; the face of the plug supports a jewel setting to run true when tightened in the chuck , for turning or burnishing operations. There is a set of plugs of assorted diameters, for all sizes of work.
sterling – 1. As applied to silver, the term denotes an alloy of 925/1000th parts, or 925/2 per cent, pure silver within the tolerances permitted by the National Stamping Act. The remaining 75/1000ths, or T6. per cent, is usually copper, though other metals are sometimes used. 2. A term used to denote money of standard weight or quality, and hence with the general meaning of approved excellence. The word has been generally derived from the “Easterlings,” the North German merchants who settled and formed a guild in London during the 13th Century, and whose coins were of uniform weight and excellence. The word, however, had been used at least as early as 1180. The “sterling” was a coin, the silver penny, 240 of which went to the “pound sterling” of silver of 5,760 grains, 925 fine, described in a statute of Edward I. Although the silver penny gave way to the copper penny, this proportion, 240 pence to the pound sterling, stayed with the British until recently when the decimal pound was adopted. The pound now consists of 100 pence.
stewartite – A variety of crystallized carbon (diamond) forming irregular black masses resembling coke, with a lower specific gravity (3.47) than diamond.
stick – The wooden holder about six inches long, to which the softer stones are cemented for cutting and polishing into gems. Facet angles are kept uniform by placing the end of the stick in a notched spindle or wooden plate, while the stone is pressed against the lap.
stick barometer – A glass-tubed mercurial barometer encased in a yard-long rod or visible casing, indicating the rise and fall of atmospheric pressure.
stippling – A variety of work comprised in the art of engraving, in which the design is formed of a series of pricks made with a steel punch.
stock – Holder for screw-threading die, with handles, for operating the die by hand.
Stockbarger furnace – Device for melting and re-crystallizing congruent-melting minerals, like fluorite and halite. It consists of an electric furnace from which a conical-tipped beaker can be lowered slowly, allowing a single dominant crystal to form and align the entire cooling melt into one crystal unit.
stock-plate – Pieces of solid or laminated metals used in jewelry work, in sheet or plate form, as furnished by manufacturers.
stone – 1. Gemology. Any substance (except pearl) which because of its color, luster or brilliance shows to advantage when polished and mounted in jewelry or other ornamental objects. Most stones of natural origin are mineral, but exceptions include coral (animal) and amber and jet (vegetable). Natural stones are classed as either PRECIOUS, SEMIPRECIOUS or DECORATIVE STONES, which see. Substitutes for natural stones include SYNTHETICS and IMITATIONS; the latter may be one naturally-occurring substance treated to resemble another, or it may be glass or plastic. 2. Horology. One of the pallets in a lever escapement. See L STONE; R STONE.
stone gauge – One of various devices for measuring the dimensions of diamonds or other gem-stones, and also, from the measurements, computing weight. Types include the caliper, slide, micrometer, stencil and dial, the latter automatically estimating the weight.
stones – In sorting rough gem diamonds, perfect octahedron crystals, regularly formed and unfractured.
stone-setting chuck – A chuck for watchmakers’ lathe with socket and screw for holding a pronged stone-setting for jewelry work, for turning a seat in the setting to fit a stone.
stop lever – The lever in a hack watch that stops the balance. See HACK WATCH.
stop-work – 1. Mechanism occasionally applied to spring-driven clocks, and often to high-grade European-made going-barrel watches, for eliminating the excess of power given by the mainspring when almost fully wound up, and the weakness of power when the mainspring is almost run down. A steel disc fastened to an elongation of one of the barrel arbor pivots has a finger projecting from its edge, that engages at each turn in one of the notches in a star-wheel that is thus caused to turn on a shoulder-screw on the cover of the barrel. After (usually) 5 turns in all have been made, the star wheel presents a tooth of a form that the finger-piece cannot pass, which stops the further running down of the mainspring in one direction, or of its winding up in the opposite direction; thus making available for driving the train, only the portion of the mainspring that delivers the most uniform power. 2. In timepieces with a fuzee, a lever that is gradually raised by the chain as it rises as wound on the fuzee; when winding has been completed, the end of the lever abuts against a finger on the fuzee top, preventing over-winding. See FUZEE.
straight-line escapement – Design of lever escapement in which the centers of balance, pallets and escape wheel are all planted in the same straight line. See RIGHT-ANGLE ESCAPEMENT.
Straits stones – Term given to poor quality diamonds from Borneo, cut in Martapoera by primitive methods.
strap-watch – A wrist-watch; particularly a men’s wrist watch with a leather or textile-fabric bracelet. See BRACELET WATCH; WRIST WATCH.
strass – A transparent highly refractive flint glass with a high lead content used to imitate diamonds or colored stone. PASTE and AMAUSE are synonymous. Refractive index, 1.58-1.68; hardness, ca. 5; specific gravity, 3.15-4.15. The colorless diamond imitation strass is at the upper end of these figures. Reportedly derived from Georges Frederic Stras (1701-1773), of Paris, whose paste jewelry achieved popularity about 1730. In 1734, Stras was appointed jeweler to the King of France; his inventions included the coloring of foils for tinting stones.
strawberry pearl – Fresh-water button or baroque pearl of pink color and fairly regular shape, but with a pimply surface. See ROSE PEARL.
streak – The mark made by a mineral on a piece of unglazed white tile; it actually shows the color of the powdered mineral. Considerably used in mineralogy, it has little importance in the gem field, since most gem minerals are harder than the tile. Hematite gives a red streak and is thus easily distinguished from composition imitations.
strike-silent hand – Hand on clock dial that can be moved as indicated on dial to operate mechanism that will silence striking, or resume it, at will.
striking – In electroplating, depositing a preliminary hard thin coat of metal on the work, by using diluted solution, as a binder between the surface of the article and the regular plating that follows by using the regular solution.
strip pallets – Pallets for escapement in inexpensive clocks, made by bending a strip of steel so that its ends form the R and L pallets; allows of manufacturing at low costs for labor and material.
stripping – 1. An operation in watch-jewel setting; after the stone is burnished into the rough setting, the metal of the exposed side of the setting is turned with a polished graver, to show as a polished slope, from the top of setting down to the surface of the stone. 2. In electroplating, a process the reverse of plating, in which metal is removed by electrolysis.
stroboscope – A device for observing periodic motion (as of balances, tuning forks, etc.) by allowing them to be seen at intervals in harmony with the motion of the moving body.
Strongite – Promotional name for synthetic spinel.
strontium titanate – One of the new man-made compounds, introduced in 1953, a congruent melting substance which forms clear, singly refracting crystals which can be oxidized to near whiteness. Though somewhat soft (5]&), it has strong dispersion (0.200) and makes a fiery diamond imitation. It is marketed under various names: Bal de Feu, Diagem, Diamontina, Dynagem, Fabulite, Jewelite, Kenneth Lane Jewel, Lustigem, Man’elite, Rossini Jewel, Sorella, Starilian, Pauline Trigere, Wellington, Zenithite, and probably others.
Stuart Range – An Australian opal locality, the site of the Coober Pedy field. The opal of this region often resembles the White Cliffs opal with a colorless to milky ground color, but is sometimes grayer. It is commonly used in opal cameos.
Stubb’s gauge – 1. A British system for measuring the diameters of round wire, drill rod, etc., used in horology; also called Birmingham gauge. 2. Steel plate with holes of graded diameters according to “Stubb’s gauge” sizes, for measuring rods or wire.
stud, hairspring – A block of metal pinned to outer end of hairspring, with friction-pivot or screw to fasten spring to balance cock of a watch.
stud-spiral – An item of jewelry findings, a mounting for a setting for a stone, etc., used for making up shirt-studs.
succinite – The mineralogical term given to Baltic amber, which yields succinic acid. A confusing use in the application of the word to an amber-colored variety of grossular garnet from the Ala Valley in the Italian Piedmont.
sugar stone – Compact white to pink datolite which forms in nodular masses, suitable for cabochons, in Michigan’s Upper Peninsula copper mines.
sulphur diamond – Misnomer for pyrite.
sun and moon watch – Late 17th Century timepiece in which the day hours were pointed to by the figure of the sun mounted on a disk revolving in a semi-circular aperture. The night hours were indicated by a figure of the moon revolving along the numerals on the dial’s outer edge.
sun opal – A variety of fire opal.
sun stone – A grayish white or reddish variety of oligoclase with many parallel oriented thin plates of hematite or goethite; their reflections give a golden sparkle to the stone. However, the term is now also applied to the clear, straw-colored labradorite found in Oregon, Utah and northern Mexico. In Oregon, but not elsewhere, some true sun-stone with its hematite spangles is associated with the transparent material.
sunk-center – Timepiece dial with the part inside the hour-circle in a plane lower than the hour circle; this together with sunk-seconds is called a double-sunk dial. See SUNK-SECONDS.
sunk-seconds – Watch dial with the seconds dial recessed so that the hand runs well below the path of the hour-hand, which is thus allowed to be set closer to the main level of the dial. See DOUBLE-SUNK, SUNK-CENTER.
supplementary arc – The portion of the circular motion of a watch balance that takes place after impulse has been given when the balance is free from contact with the escapement.
surface blemish – Any fault on the exterior of a polished diamond, such as cavity; nick; external grain, knot or twinning line; scratch; wheel mark; natural; bearded girdle; girdle chip; concussion mark. Extra facets and slight polishing marks are sometimes regarded as factors in cutting grade, rather than in clarity grade. Surface blemishes are also called external characteristics, surface marks or finish faults.
Sudani garnet – Syriam garnet.
surprise piece – An attachment to the quarter-snail of a striking or repeater watch, for insuring against accidental errors in number of strokes sounded.
surveying chronometer- A box chronometer with addition of electric contacts that may be sent by wire or loud-speaker to an observer at a distance, for determining longitude on land, or other surveying uses.
suspension – 1. The parts of a clock pendulum that have to do with supporting it as its upper end. 2. The parts of a marine chronometer that connect the inner metal case of the movement with the outer case of wood; usually an intervening metal hoop or ring, with pivots and bearings set at quarterpoints on the ring. See GIMBALS.
swaging – Working metals into desired shapes by hammering cold metal into a usually rather simple form or mold made of harder metal. Swaging does not mean power die-press work on cold metal, because the force is applied with a hand-hammer; nor does it mean handwork on hot metal, which is properly called forging.
swaging block – Steel block with graduated grooves for shaping metal. The grooves may be patterned for making embossed molding.
sweating – Soldering by coating both surfaces thinly with solder; then binding them together, cold, and applying heat with flux to lead the solder between the surfaces.
sweep seconds – A hand driven from center of movement, of length equal to the radius of the minute circle on its dial, indicating seconds or seconds and fifths on the circle, making one turn on dial in one minute; used in chronograph watches, timer watches, or clocks.
sweet-water pearls – Fresh water pearls.
swindled stone – A diamond with a large spread and little depth, made to look like a much heavier stone than it is.
swing – In a lathe, the measurement of its capacity to handle diameters of work; “four inch swing” would mean 4 inches height from top of lathe bed to center of spindle; which would accommodate work of a maximum diameter of eight inches, for facing work; or of smaller diameters for some work on edge or side, allowing for height above bed of the tool rest, slide rest, etc.
swing-tool – A metal bar supported at its ends on pointed pivots in bearings in a frame. Work to be filed or lapped truly flat is cemented or screwed to the bar; the pivots allow a slight swinging motion so that the work accommodates itself to the flatness of the acting file or lap, preventing formation of rounded corners at edges of work.
Swiss cut – 1. A type of diamond cutting which has an octagonal table and 24 facets on the crown, with 16 facets on the pavilion, a total of 42 facets, including table and culet. 2. Also, with 16 facets and table on top, for a total of 34 facets including table and culet.
Swiss lapis – A fradulent and widely used term for reddish or grayish chert or jasper dyed blue to imitate lapis lazuli. It can be distinguished by its higher luster, the lack of pyrite inclusions, and the frequent presence of small knots of quartz crystals which do not take the dye, and hence, remain white or gray. German lapis is the same sort of material.
swivel – An item of jewelry findings, for attaching watches, etc., to chains; usually with a loop of metal having a hinged section that may be opened to insert a watch case bow, or a ball or ring; and that is normally held closed by a spring. The closed end of the loop is fastened usually to a jump-ring on a base that is free to turn.
swivel-vise – A bench vise with jaws on a base that may be turned and fastened in any position, for convenience in getting at work.
Sydney shell – Macassar shell.
synthetic – A term applied to an artificially made substance which has all the physical properties and the chemical composition of a natural substance. Synthetic gem stones should be sharply distinguished from imitation stones; the former are physically and chemically identical with the natural material, while the latter are similar only in appearance. Curved striae, or lines of growth, and frequently-rounded bubbles show synthetic origin by flame fusion. Rule 39 of the Federal Trade Commission’s Trade Practice Rules for the Jewelry Industry (1957) forbids use of the word “synthetic” with the name of any natural stone unless the product has essentially the same optical, physical and chemical properties as the stone named. (In recent years, certain new man-made substances with gemstone characteristics have been made in laboratories with modern equipment and sophisticated techniques. When they have been cut and set in jewelry, they, too, have been designated as “synthetics,” although several, like YAG and strontium titanate, have no known natural counterparts. Even the spinel and rutile made by the Verneuil process is unlike the natural material. Calling these products synthetics is an unwarranted extension of a term which was ill-conceived at the outset, but which, in time, came to be generally understood to be defined as above. The newer man-made materials have a place in the trade, for they have great merit, and deserve their own name.— F.H.P.)
synthetic alexandrite – A flux chrysoberyl with the proper impurities to give it the changeable effect of a natural alexandrite. Marketed by Creative Crystals Inc. in 1973, it is one of the new class of expensive synthetics, like the flux-grown rubies and emeralds. For many years there had been a synthetic sapphire material with impurities which gave it an alexandrite-like color change, and these have been widely sold as synthetic alexandrite. Imitation alexandrites of Verneuil-grown corundum are inexpensive, common, and not too good on the change. The true synthetic must be recognized as something very superior if it is to bring the price it deserves.
synthetic corundum – A synthetic product with the chemical composition of the natural mineral, aluminum oxide, and the inclusive term for numerous gems like synthetic sapphire and ruby. Synthetic corundum gems with impurities to color them in imitation of non-corundum gemstones cannot properly be called synthetic, as for example, the so-called “synthetic alexandrite,” which is really imitation alexandrite. See AMARYL; BIRNE; DANBURITE; FORMATION STRIATION; FREMY RUBY; SCIENTIFIC RUBY; RECONSTRUCTED RUBY, etc.
synthetic diamond – 1. Industrial. Microscopic crystals, sold in competition with natural bort, commercially produced in 1953 in Sweden and thereafter in the U.S., Holland, South Africa, Soviet Union, Japan, China and elsewhere. True synthetics, they are not to be confused with imitation diamonds of various man-made materials like YAG, titania and strontium titanate, although some advertisements for the latter appear to read ambiguously and suggest erroneously that the softer imitations can be called synthetic diamonds. 2. Gem quality. Regularly shaped cubic and octahedral crystals of gem quality, weighing up to two carats, in black, green, yellow, amber, gray, blue and white, made after 1970 by General Electric Company. Announced goal: electro-conductive and semi-conductive stones for electronic use. Announced cost, according to Dr. Arthur Bueche of G.E.: 10 times that of natural stones. See MAN-MADE.
synthetic emerald – Since emerald melts incongruently, the compound has to be synthesized by one of the more costly processes, either flux grown or hydrothermally, and true synthetic emeralds are, therefore, expensive. They can be recognized by typical bubble swarms, but do have straight lines, unlike the Verneuil-grown rubies. For many years, all manner of imitations were sold under the blanket term synthetic emerald, a gross misnomer, for which jewelers are now paying with public confusion about the nature of the true synthetic emerald and dismay, initially, at their high cost. The makers, too, have had to resort to such circumlocutions as “created” or “cultured” to overcome the bad image that accompanied the long used custom of calling any green imitation a “synthetic emerald.” See CHATHAM, CARROLL F.; GILSON, PIERRE.
synthetic opal – Perfected in 1972 by Pierre Gilson, of France and Switzerland, the true synthetic opals, both black and white, are excellent reproductions of the natural stones and are true synthetics. They must not be confused with various imitations, usually of glass, or compositions, like doublets and triplets, in which part of the material is natural opal.
synthetic ruby – A synthetic reproduction of the natural material. It can be distinguished from the latter, from the presence of curved growth lines and. often, round bubbles, but has almost identical composition and properties. This term cannot be applied to any other type of imitation of the natural ruby. Flux fusion and hydrothermal techniques have added another dimension to ruby synthesis, and we now find a new class of stones, sold most often as crystals, either singly or, after 1966, in clusters, that command far higher prices than the older Verneuil synthetics. Clusters of ruby crystals do not occur in nature, so there is no problem about distinguishing the synthetics of this type. Cut stones will usually show the veil-like flux inclusions noted in alexandrite and emerald flux-grown crystals and, hence, be distinguishable. Flux-grown “Chatham-Created” ruby crystals, as large as 20 carats, were announced by Carroll F, Chatham in 1970. See VERNEUIL, A.; CHATHAM, CARROLL F.; BROWN, H. TRUEHART.
synthetic rutile – A Verneuil-grown (usually) boule of titanium dioxide (or titania, for short) which, by great purification and heat treatment with the addition of a bit of alumina, can be made in a pale straw color; discovered in 1948 during search for a better whitener for paint than lead oxide. They are widely sold as imitation diamonds under a variety of names. Double refraction is strong, they are not completely clear, and dispersion is very strong, making them unnaturally fiery. At best they are distinctively yellow and with their exaggerated dispersion, double refraction and slight cloudiness, they cannot rival the diamonds they are said to simulate for clarity and brilliance. The best of the synthetic rutiles are colored; the blues and golds are magnificent.
synthetic sapphire – See SYNTHETIC RUBY.
synthetic spinel – Synthetic magnesium aluminate, but with a higher alumina content than natural spinel, hence, not quite identical in properties. The coloration of this material is usually different from any natural stones, pale blues (sold as “synthetic aquamarines” or “synthetic zircons”), and other light colors being the rule. See AQUAGEM; BERYLITE; DIRIGEM; ROZIRCON; etc.
synthetic turquoise – Formerly, imitations of tur¬quoise were either dyed or compressed compositions of various types, but in 1972 Pierre Gilson of France and Switzerland succeeded in precipitating and consolidating a phosphate with the composition of true turquoise and marketed it as synthetic turquoise. Many of the stones are detectable by their characteristic inclusion of tiny dark blue specks here and there on the surface, but the properties are the same as those of natural turquoise of the better qualities and were it not for a characteristic granular texture and the black specks it would be hard to recognize.
syntholite – Trade name for the synthetic corundum imitation of alexandrite.
Syriam, Syrian garnet – Almandine garnet, an ancient, commonly mentioned and exceedingly questionable locality name, derived from the name of the capitol of the old kingdom of Pegu (Lower Burma).