Posted June 11, 2014 by Esslinger Staff
taaffeite – (tar’fite) A rare violet, doubly refracting, beryllium magnesium aluminate found as a few cut stones, usually considered pale spinels, in Sri Lanka gemstone parcels. Only a few are known though it has been found in a rock in China, in non-gem quality. Its hardness is about 8; refractive index about 1.722 and 1.7185 (weakly doubly refracting, the method of distinguishing it from spinel); and a density of about 3.60. It appears to be hexagonal.
tabasheer – Amorphous, opal-like silica, found in the joints of certain species of bamboo. It is white to bluish-white in color, and becomes transparent when saturated with water. In many respects it resembles the natural mineral substance hydrophane.
table – The large horizontal top facet of a faceted gemstone. In an ideal round brilliant cut diamond, the diameter of the table is equivalent to 53% of the diameter of the girdle, according to proportions devised in 1919 by Marcel Tolkowsky and favored by some American cutters and the American Gem Society. The approved diameter of the table is 57.5% of that of the girdle, according to “Scan. D.N.” standards proposed in 1970 by Scandinavian jewelers. Table measurement is from corner to corner.
table diamond – An early form of diamond cutting, the octahedral point being worn down to square, the opposite point to a very small plane and the sides squared up, the width of the two sides together equaling the upper plane surface. Flat stones, or lasques, omitted the lower part.
tablestone – Refers to an ancient form of cutting, and to the flat modern ring stones, often with insets of metal or gems, and frequently engraved.
tacking machine – Light positioning and welding device used prior to soldering. Eliminates need for binding wire or soldering jigs in joining parts to be soldered.
Tahiti shell – Shell of a variety of Margaretifera found in the south Pacific, with a green nacre and black edges. Variously called Gambia, Auckland or Tahiti shell, depending upon the export centers.
talc – A very soft (1 on Mohs hardness scale), light-colored hydrous magnesium silicate. It is crushed for talcum powder, etc., and the impure massive variety is known as STEATITE or soapstone.
tallow drop – A cabochon cut stone.
tallow top – A low cabochon.
tampon – The pivot-plug in a cylinder staff. See CYLINDER ESCAPEMENT.
tang – 1. The pointed end of a file, graver or other tool that is driven into the wooden handle of such a tool. 2. Diamond cutting. A device by which a diamond is held against the polishing wheel; the tang resembles a squat, three-legged stool, two of the legs being adjacent to the wheel, while the diamond to be polished is soldered to or otherwise held in the third leg and held against the wheel.
tangential – A principle in designing escapements whereby impulse force is to be applied in a direction coinciding with a tangent to the circle representing the path of motion of escape wheel teeth at the point where contact of parts is made.
tangiwai – Dark green, nephrite-like serpentine found in New Zealand.
tanzanite – A gem variety of the mineral zoisite, the first source of which was discovered, on July 2, 1967, in the Meralani Hills of Tanzania; it was named by Tiffany & Co. of New York. It has a hardness of about 6, and refractive indices of 1.6917, 1.694-5 and 1.704. It has one very easy cleavage and is strongly trichroic in blue, violet-ish red and yellowish. Heating reduces the pleochroism and makes stones that are just blue and violet. Most stones are heated. Gems of up to 50 carats have been cut, but most are smaller. Despite its glassy look, relative lack of hardness and easy cleavage, it has been promoted successfully.
tap – The tapered hard steel screw with fluted, hollow cutting edges to cut threads in a hole.
taper – 1. A form in which there is a gradual and uniform decrease in diameter from end to end. 2. A metal piece to fit in taper-chuck or tailstock spindle to form a center for lathe work. See TAPER CHUCK; TAILSTOCK.
taper chuck – Chuck for watchmaker’s lathe; of solid steel except with an axial tapered hole for holding taper-centers, taper-shanked drills, etc. See CENTERS, LATHE; TAPER.
tapered baguette – A tapered modification of the regular baguette.
tapered pentagon – A type of pentagon cut obtained by varying the length and angles of sides.
tarnish – The thin film of color on the exposed surface of a metal. In most cases the film is a metallic oxide. The tarnish that forms on silver, however, is silver sulphide.
Tasmanian diamond – Misnomer for white topaz.
Tauridian topaz – Pale blue Russian topaz, an allusion to the locality.
taxoite – Green serpentine, from Chester County, Pa.
T-bridge – The typical shape of the suspension scaffold on a Willard clock.
tecali – Coined name for the dyed Mexican onyx marble, which has been widely sold under the name of Mexican jade. It is derived from the name of the locality where it is found.
teeth – In gearing, the cogs on a wheel, differentiated from “leaves,” which are cogs on a pinion.
Teflon – Trade name for polytetrafluorethylene, a plastic substance with “friction-free” surface, applied to some mainsprings termed “permanent lubed.”
tektite – A naturally occurring siliceous glass fragment, thought to be of meteoritic origin. Moldavite and queenstownite are tektites.
tempering – Reducing the hardness of hardened steel, by gradual heating to stages less than annealing heat. The control in tempering is (1) by observing changes of color on surface of steel, from shades of yellow, then gradually darker, through brown and purple to blue, as heating is continued; (2) by the effect of heat on oil surrounding the steel—the changes in smoke, flame, etc.; and (3) in manufacturing quantities of work, by using heat-indicating instruments, like a pyrometer. Usually steel that is hardened and tempered is described simply as “tempered” steel. See HARDENING; PYROMETER; STEEL.
template – Pattern used for outlining the shape of the form of work to be done on a piece of material; for example, in making a new flat spring the parts of a broken spring may be cemented together to the sheet steel and used as a template, to scribe the outline for sawing out the new spring.
templet facet – Another term for bezel facet.
T-end – The endpiece of a mainspring with pivots extending into and pivoting in holes in the barrel floor and cover.
tension spring – A thin spring pressing lightly on a center seconds post to prevent backlash of the seconds hand.
terminal curves – The various forms given to the outer end of balance springs of the Breguet or overcoiled type; and (rarely) also to the inner end of Breguet springs; and to both ends of helical (cylindrical) balance springs in chronometers. Various specific curve forms have been found to promote isochronism of vibrations controlled by balance springs with such terminals. See ISOCHRONISM; PHILLIPS, EDOUARD.
termination – In a minerological sense, a crystal termination includes the faces at the end of the crystal. One may speak of a terminated beryl crystal, by which is meant a more or less unbroken crystal with terminal natural plane faces, rather than a broken end or a polished end.
testing-needles – Sets of metal points tipped with various karat-grades of gold, for use with stone and acid for determining the karat-quality of gold, mostly in making appraisals of scrap-value of old jewelry and watch cases. See TEST STONE.
tetragonal system – (te-trag’on-al) One of the crystal systems, similar to the isometric except that one of the three mutually perpendicular axes is longer or shorter than the other two. The characteristic crystal of this system, then, is square when viewed from above, and prismatic or tabular when seen from the side. Vesuvianite, zircon, and scapolite are among the gem minerals which crystallize in this system.
Texas agate – A banded jasper found as gravel in the Pecos River, Texas.
textured finish – Karat gold. Various surface treatments for karat gold, especially of 18 karat fineness, popularized during the Nineteen Fifties. Used separately or in combination with bright or other textured finish, their types include: Florentine, bark, granulated, woven, nugget, diamond-hammered, pressed mesh, applied, and machine-faceted.
texturing – A means of surface decorating jewelry. Various textures are obtained by means of hand engraving and the use of texturing burs and wheels. These wheels either have evenly spaced teeth or are impregnated with diamonds which cut into the metal. Texturing is most often done on the diamond faceting or decorating machine.
thallite – Yellowish green epidote.
thallium malonite – An organic compound of thallium, which, when mixed with thallium formate, makes the heavy liquid commonly known for its discoverer Enrico Clerici, as Clerici’s solution. At room temperatures it has a density of 4.25 and may be mixed with water in any quantity to reduce the gravity. One of the most useful of the heavy liquids for gem testing, but exceedingly toxic.
thermoluminescence – Luminescence caused by heat, too low to cause incandescence. A variety of fluorite known as chlorophane glows white or green when lightly heated in the dark.
thermometer curb – Early compensating device for watches; a bimetallic arm carrying a pin which changes its distance from a fixed pin with any changes of atmospheric temperature; the outer hairspring terminal is in the space between these pins, which by becoming narrower quickens the rate, or wider, slows the rate, to compensate for effects of heat and cold on hairspring. See COMPENSATION
Thetis hairstone – A colorless quartz containing tangled balls and threads of green hornblende, the name of the sea goddess being, perhaps, an allusion to a seaweed-like effect in the stone.
thiosauite – Anorthite from Iceland.
third wheel, pinion – In a watch of standard design, the wheel or pinion that is driven by the center wheel, and that drives the fourth pinion and wheel.
thomsonite – A zeolite mineral, a hydrated calcium, sodium, aluminum silicate, fairly common as a mineral but of gem interest only because of an occurrence in amygdule and as waterworn pebbles on the beach of Isle Royale in Lake Superior. The mineral forms fibrous, banded masses in red, white and green, makes attractive cabochon stones, mainly appreciated by local collectors. Hardness, 5-5.4; specific gravity, 2.3-2.4. See COMPTONITE; LINTONITE.
Thoulet solution – (thoo-lay1) A saturated solution of potasium iodide and mercuric iodide in water for specific gravity determinations. It forms a clear, amber-colored liquid with a maximum density of 3.196 and a refractive index of 1.733. It is miscible in any proportion with water and may be concentrated again by gentle heating, in a sort of double-boiler arrangement, known as a water bath.
thread setting – A type of setting where the edge of the bezel or frame or outer edge of bead-work is cut to a fine edge before millgraining. A bright cut edge for millgraining.
three bead setting – A development of the square prong setting. Each corner post instead of remaining flat on top is formed into three round beads. The corner itself forms one bead with the other two adjacent to it at the side toward the diamond.
three-facet cut – A simple type of rose cut, with but three faces in a low pyramid.
three-flute drill – A twist drill with three spiral grooves instead of the customary two grooves.
three-fold brilliant – Ideal brilliant.
three-grainer – A diamond weighing about .75 ct.
three-legged escapement – A gravity escapement for tower clocks and regulators, with three weight-arms for giving impulse to pendulum. A later form is the double three-legged escapement. See GRAVITY ESCAPEMENT.
three-phase inclusion – Gemologists speak of some stones, notably Colombian emeralds, as having “three-phase inclusions” by which they mean that they find voids within the crystal filled with liquid, a movable bubble, and a small cubic-seeming crystal which rarely tumbles about as the stone is tilted.
three point diamond – A brilliant cut stone whose table is parallel to the octahedral direction.
three-quarter plate – Design of watch movement in which the framework with upper pivot bearings is made in two or three sections fastened separately to the lower plate, with top of balance cock in same plane as tops of plate sections. See BAR MOVEMENT; FULL PLATE.
three ridge mussel – The common name for the best species of American pearl-bearing freshwater mussel, also known as the blue point mussel (Quadrula undulata and Quadrulaplicata).
three-square – Trade term for a triangular file.
throw – A large, hand pulley wheel to impart power to a lathe.
thulite – (thoo’lite) A rose pink variety of the calcium aluminum silicate, zoisite. It occurs in Norway and elsewhere in pink masses and embedded crystals and has been used as a decorative stone. The refractive index is about 1.700, the specific gravity 3.12 and the hardness 6 to 6 1/2. Named for Thule, ancient name for Norway. See TANZANITE; ZOISITE.
tiara – A piece of feminine jewelry worn on the hair, usually set with gems; a small form of crown, a modification of royal or ecclesiastical crown, used for personal adornment without official significance.
tic-tac – An escapement in which the pallets span but few teeth to effect a wide arc to the short, pivoted pendulum.
Tiffany setting – A six-prong setting generally round in shape and flaring out from the base to the top, having long slender prongs that hold the stone. Sometimes applied to four prong settings as well.
tiffanyite – Name given by G. F. Kunz to an indefinite substance in phosphorescent diamonds which was supposed to be responsible for the phenomenon observed after excitation by ultraviolet light.
tigerite – Tiger eye.
tiger’s-eye – Name given to the golden silky-looking quartz resulting from the alteration of blue, fibrous crocidolite asbestos in deposits near Griquatown, north of the Orange River, South Africa. The coloration is caused by limonite, the hydrous iron oxide. Heating is said to drive off water and turn the stone red, the limonite changing to hematite. Bluish and greenish material is also sometimes seen; some of the coloration may be artificial.
timepiece – A watch or clock; particularly, one that tells time only, and has no striking mechanism.
timer – 1. A chronograph watch, stop-watch, sport-watch, etc., with mechanism to stop a running second-hand. 2. A workman who specializes in adjusting watches.
timing – Term used comprehensively to mean the theory and practice of applying and adjusting balance springs, and pendulums, for accurate timekeeping of watches and clocks.
timing washer – A pierced disc of thin metal, used to place on balance screws to increase weight and make the watch run slower; same weight of washers must be placed on opposite screws, to maintain poise.
tin – A soft, bluish-white metal, easily worked in the cold state. It does not oxidize in air. Its melting point is 450°F. The jeweler is likely to encounter it in soft solder, pewter and bronze.
tincture – Foil-backed.
tin-lap – For polishing flat steel parts, a block of pure tin, with surface planed, filed or scraped flat; rouge or diamantine mixed to a thick paste with oil is spread thinly on lap, and the gray-finished work rubbed over the lap; properly done, this produces a “black” polish. See LAPPING.
tin oxide – Also called putty powder; an abrasive for producing a fine luster on stones, or metals, used as final polish.
tin stone – Cassiterite.
tint tool – Graver for cutting massed lines for shading engraved work, with, edge and tang angled so the handle will clear flat surfaces.
tip-over rest – A tool-supporting rest for watchmakers’ lathe, in which the T can be quickly swung on a hinge to be out of the way for making measurements, and quickly swung back to resume turning, without wasting time in making adjustments each time. See T-REST.
titania – A synthetically produced rutile. A brilliant, transparent stone with a refractive index of between 2.62 and 2.90. They are strongly doubly refracting and have a hardness of 6.5. Colors range from a light straw color, through orange brown to a brilliant blue green. See SYNTHETIC RUTILE. Promotional names are numerous; they include Astryl, Brilliante Diamothyst, Gava Gem, Jarra Gem, Johannes Gem, Kenya Gem, Kima Gem, Kimberlite Gem, Lusterite, Miridis, Rainbow Diamond, Rainbow Magic Diamond, Rutile, Sapphirized Titania.
titanite – (ti’tan-ite) Sphene.
toad’s eye tin – Botryoidal reddish tin ore, with a concentric structure, suitable only for cabochon cutting for collectors.
todo mundo – Brazilian term for common leaf-green tourmaline from Salinas in Minas Gerais.
toe – The front end of a club-tooth of escape-wheel in lever escapement; or of a tooth of escape-wheel in cylinder escapement.
toggle chain – A short piece of chain connecting two parts of an article of jewelry, like the piece between the buttonhole bar and the long chain of a watch vest-chain.
Tokay luxsapphire – A brownish-black Hungarian obsidian.
tolerance – 1. The permissible variation of an object in some term, such as hardness, weight, or quantity, a. Gold. In the U.S., the National Stamping Act, as passed in 1906, permitted considerable latitude between the marked and the actual gold content of a karat gold object. The fineness of the gold could be a half-karat (nearly 21 parts per 1000) less than the fineness marked on the article, box or tag (except that for watchcases and for flatware the actual fineness must be within 3 parts per 1000 of the fineness marked). If the article is soldered, the entire article, including solder, might assay as much as one karat (nearly 42 parts per 1000) less than the fineness marked. Britain and Switzerland permit no tolerance for gold alloys; Denmark permits a tolerance of 2 parts per 1000; Norway, Italy, Belgium, Spain, Holland, France and many other nations allow a tolerance of 3 parts per 1000. b. Silver. The National Stamping Act, as passed in 1906, permitted a tolerance of 4 parts per 1000 for articles made in whole or part of silver and of 10 parts per 1000 if soldered. 2. Lead tolerance. The maximum proportion of lead recommended by the Food and Drug Administration for articles used with food: 7 parts per million, in a 24-hour test, with an acetic acid leaching solution. Excessive lead has been detected in dinnerware, leached from decorations or rarely the clay; in silverplate hollow-ware, leached from lead-tin solder and in the case of some imports, from the base metal itself; and in pewter, leached from lead-tin solder. Lead-free solders were developed in the mid-Nineteen Seventies, that for pewter being 76% tin, 24% bismuth.
toluene or toluol – (tol’you-een) A light-weight hydrocarbon with low surface tension, related to benzine which is commonly used in place of water in the determination of specific gravities, especially of very small stones; also used as a solvent for some plastics.
tomb jade – A name applied to jades which have, at least theoretically, been buried for many years, during which time the coloring matter has oxidized from its original greenish hue to a red or brown. Many archaic pieces show this effect and are so denominated; but the purchaser should be wary, for it is easy to imitate archaic work, and deceptive coloration is simple.
tool post – On a lathe sliderest, the slotted column with bolt at top, for holding cutting tools.
tool steel – Steel, capable of being hardened and tempered, used in making fine tools, dies and springs. See STEEL; DRILL ROD.
top cape – Early diamond color-grading designation between crystal and cape, the yellowish tinge being visible to an unaided eye.
top crystal – Early diamond color-grading designation between Wesselton and crystal, indicating a slight yellowish tinge.
topaz – (to’paz) An aluminum fluosilicate crystallizing in the orthorhombic system. It is one of the well-known pegmatite minerals, most often white or blue, sometimes yellow, brown, orange or pink. It is number 8 in the Mohs hardness scale; its refractive index is about 1.62; its specific gravity 3.53. Commonly confused with citrine or “topaz” quartz, but the latter is far softer, lower in refractive index and many times more common. Brown stones of Brazil may be made pink by heat. Naturally pink topaz in cuttable quality was found in Afghanistan in 1973. Brazil is the chief source of the gem, it being sold as “precious topaz” to distinguish it from the more common quartz gem. Other names include aquamarine topaz for the blue stones, now commonly sold as aquamarine, Brazilian ruby, Brazilian sapphire, Saxon chrysolite.
topazolite – A greenish yellow to yellow brown variety of andradite garnet, so far of no gem significance because it has not been found in gem qualities. See DEMANTOID.
topaz quartz – Trade term for the citrine quartz or heated amethysts of a brown to golden color, often sold under the guise of “topaz.” See CITRINE.
topographic agate – A variety of fortification agate, with very fine lines resembling contour lines on a topographic map of rugged country.
top plate – In a full-plate watch, the plate with pivot-holes, etc., that is opposite to and parallel with the pillar-plate, or lower-plate. See FULL-PLATE.
top Wesselton – Early diamond color grade, just below river or jager.
torch – A portable device in which a fuel gas and oxygen or air are combined to produce an intense flame. Used for welding, melting and soldering of metals.
torque – The twisting force or turning effort of a spindle, as in a lathe, motor, etc.
tortoise shell – The mottled brown and yellow horny plates which make up the shell of a carnivorous inedible sea turtle known as the hawksbill turtle (Chelonia imbricata) found in tropical and subtropical seas. It is easily molded and shaped when hot and is used for fine combs and jewelry; also for lathe laps, with diamond powder, for polishing hard stone parts of watches and clocks, such as pallet stones, faces of bearing-jewels, etc.
Tosa coral – Name applied to Japanese coral of moderate quality. See MORO CORAL; BOKE.
total reflectometer – An instrument for making accurate determinations of refractive indices, by measuring the angles of total reflection in cut stones.
total lock – In action or adjustment of lever escapement, the amount or distance by which a pallet stone has gone toward the escape-wheel center at the time when the lever has come to rest against a banking, which prevents further movement of the pallet. For total-lock, some authorities use the term “lock-plus-slide.” See ACTUAL LOCK; DRAW; DROP-LOCK; LEVER ESCAPEMENT; SLIDE.
total weight – As descriptive of diamond jewelry, the combined carat weight of all the diamonds in the piece. It is an unfair trade practice to represent the weight of all the diamonds without the words “total weight,” so as to indicate clearly that the weight is that of all the stones and not that of the center or largest stone.
touchstone – A hard black stone, basalt or jasper, ground to a smooth but not polished surface, on which gold or silver can be tested by comparing its streak with that of known alloys in touch needles. Also known as basanite and Lydian stone.
touch watch – A watch with raised studs at dial numerals, and a heavy hand, for reading time in the dark, or by a blind person, by feeling with a finger. See BRAILLE WATCH.
toughness – As distinct from hardness, which is affected by cleavages and brittleness, toughness refers to the durability of a stone for hard usage. The texture, interlocking crystals, of jade gives it a toughness unequalled by other, harder, stones, and while it may lose its polish, it is unlikely to fracture, as harder stones might.
tourbillon – Design of watch movement in which the balance and escapement are mounted in a framework that is turned continually as the watch runs; so that it averages and corrects the vertical position errors by varying the conditions that produce them, usually once a minute. Invented by A. L. Breguet in France in 1781. See BREGUET; KARUSSELL.
tourmaline – (toor’mal-een) One of the most important of the gem stones, a complex sodium aluminum borosilicate which is found in pegmatite dikes. It comes in many colors, the commonest of which is black. However, the complex pegmatites with lithium and similar rare elements are characterized by highly colored green, red, pink or blue prismatic rhombohedral and hemimorphic crystals of tourmaline, a lithla-bearing variety now known more specifically as elbaite. Often the color changes through the crystal, and differently colored bands, either concentric or in the length of the crystal are frequent. Its hardness is 7 to 7 1/2; specific gravity, 3.06; refractive index about 1.63. Brazil, East Africa, Maine and Madagascar have the most important deposits known today. There are many misleading names given to tourmaline to make it sound like something else, for example: Brazilian emerald, Siberian ruby, Ceylon chrysolite, and Brazilian sapphire.
tracer – 1. Steel point like a pencil, for drawing designs on metal for engraving. 2. Punch with broad flat surface, used with hammer to flatten thin metal-work in bottom of a recess. 3. Chisel-like punch used with hammer to incise outline of design prior to chasing or repousse.
trade mark – The mark of a manufacturer, importer, wholesaler or retailer registered with the United States Patent Office. Registration remains in force for 20 years; may be renewed for like periods. The National Stamping Act of 1906, as amended in 1961 to pinpoint responsibility for quality markings, requires that quality-marked articles made of gold or silver must also be trademarked.
Trade Practice Rules – Rules for the jewelry industry, designed to protect trade and public from unfair or deceptive acts or practices, promulgated by the Federal Trade Commission June 28, 1957, amended Nov. 17, 1959. The first trade practice proceeding of any sort ever held by the FTC took place in Providence, R.I., in 1916 at the request of the jewelry industry.
train – In a watch or clock, the series of wheels and pinions between the power-plant (mainspring or weight) and the escapement. This is what is meant by saying merely “the train,” although it is sometimes called the “time-train.” There are other gear-trains in some horological mechanisms, but these are always referred to, qualified as to their special purposes, like “dial train,” “striking train,” etc. The time-train progressively multiplies turns made by gears, so that the mainspring or weight barrel has to run much more slowly than the escape wheel at the other end of the train, which results in requiring a long period of time for the power to run down, hence the timepiece does not have to be rewound inconveniently often, which is the purpose of the train. 2. The number of beats-per-hour made by a watch balance or clock pendulum; as “18,000 train.” See DIAL TRAIN COUNT; STRIKING WORK.
trainite – Trade name for a mixture of vashegyite, a hydrous aluminum phosphate, with a colloidal zeolitic mineral. Green in color, and marketed from an occurrence near Manhattan, Nev., it was originally considered a banded variscite Also called sabalite.
trammels – Dividers of extra large capacity, the points supported adjustably on a wood or metal beam, instead of on limbs jointed together at one end as in ordinary dividers.
transducer – The section in an ultrasonic machine which receives electrical energy and transforms it to ultrasonic mechanical vibrations.
transfer pad – A block of printers’ roll gelatine, molded with flat top surface, for duplicating designs to be engraved. For example, if a dozen pieces require the same engraving, the first one is cut; the cuts filled with powdered chalk; this is pressed against the pad, depositing the design laid in powder on the pad. The other pieces are dabbed with tallow, then laid against the powder design, which will print itself from the tallowed surface onto the metals, saving labor of drawing the design repeatedly.
Transvaal jade – Misnomer for a compact green grossular garnet, often with small bits of black chromite in the mass, which forms in seams in chromite rock In a similar way there is also massive pink grossular in the same area, in the South African Transvaal.
trap brilliant – A roughly circular stone with the facets parallel or step cut.
trapeze – A fancy diamond cut with the outline of the girdle and the table in the shape of a trapezoid or truncated triangle.
trapiche emerald – A twinned emerald growth, six sections surrounding a central core. Corner edges may be decomposed and filled with a clayey mixture of other material, creating in cross-section a six-rayed emerald star with white material between the rays. Usually very small.
traverse grinder – An attachment for watchmakers’ lathe; a spindle freely movable lengthwise, with pulley for driving by belt from countershaft, has mounting at one end for abrasive wheels or laps, and at other end a finger-knob for controlling the application of laps to work. The spindle bearings are on a base that may be turned and locked to angular positions for grinding tapers. The tool is really a large-sized pivot polisher, for grinding and polishing heavier work than on pivots. See PIVOT POLISHER.
traversellite – Green clear diopside, from Traversella, Piedmont, Italy, apparently rarely suitable for cutting.
travertine – A decorative marble, sometimes used in small objects and colored to bring out the banding it owes to its water-deposited origin. More commonly it is used architecturally, but is not especially suitable for this use because of its many holes which are soon filled with dirt.
treadle – A fly-wheel pulley turned by crank levers and foot pedal to operate a lathe or machine.
treated stones – Gemstones that have been subjected to any sort of treatment to change their color, or to render flaws inconspicuous. Some treatments cannot be detected by any test. But there is no question that treatment should be disclosed if it is impermanent, or competes unfairly with a naturally occurring product. See BLEACHING; DYEING or STAINING: HEATED STONES; IRRADIATION; LASER-DRILLING; LEACHING; OILED STONES; PAINTED DIAMONDS; PARAFFIN TREATMENT.
treated turquoise – Much well-colored turquoise owes its hue and polish to impregnation with paraffin, oil, liquid plastic, glycerine, or sodium silicate; or, if beads, to Berlin blue dye coated with clear plastic. It is said that all well-colored turquoise with specific gravity below 2.60 owes the intensity of its hue to artificial treatment. A hot needle near such a stone causes the paraffin or oil to melt or flow; touching the surface of a plastic-impregnated stone produces a sweetish odor.
tree – In jewelry manufacture, a cluster of wax patterns attached to a body of wax, enabling multiple castings to be made. See LOST WAX.
tree agate or tree stone – MOCHA STONE.
trefoil – Design for clock hands resembling a three-leaf clover.
tremolite – (trem’o-lite) A light-colored calcium magnesium silicate member of the amphibole family, commonly found in metamorphic rocks. A compact variety constitutes in part nephrite jade; see ACTINOLITE. It is rarely transparent enough for facet cutting but cabochon material is abundant and often attractively colored; green, blue, violet, etc. Hardness, 5-1/2 to 6; specific gravity, 2.9 to 3.2; refractive index, about 1.61.
Trenton diamond – Misnomer for Herkimer County, N.Y., rock crystal.
T-rest – In a hand-rest for using gravers in watchmakers’ lathe, the adjustable T-shaped bar which directly supports the graver while it is cutting the work. See L-REST.
triangle – A fancy diamond shape. A peak triangle has a base shorter than the sides, while a flat triangle has a base longer than the sides.
triangular file – A three-sided file, tapering to a point. Made in hand, needle and escapement sizes. See THREE SQUARE.
triboluminescence – A luminescent phenomenon observed in some substances when they are stroked or scratched with a hard point. Two flints rubbed together will emit flashes of light, as will some diamonds.
trichlorethylene – A colorless, toxic fluid used as a degreasing agent.
trichroism – The more accurate term for dichroism when dealing with mineral crystallizing in the orthorhombic, monoclinic and triclinic systems. It refers, logically enough, to the three different colors observed in colored minerals, in the different optical directions. See DICHROISM; PLEOCHROISM.
triclinic system – A crystal system with lowest symmetry of all; there are three unequal axes inclined toward each other, and a center of symmetry. The feldspars (except orthoclase), axinite, kyanite and rhodonite crystallize in this system.
trig – To stop the motion of a wheel or train of gearing, by placing a wedge under a wheel, or a pin in its spokes, as when inspecting the action of escapement or balance, or during shipment of a timepiece to prevent breakage of balance or escapement parts.
triggering coil – The phase-sensing coil in an electronic, sonic, balance or pendulum timepiece.
trigon – Equilateral triangular indentation on the surface of a diamond octrahedral face. Nearly every face has such growth marks, some visible to the unaided eye, far more of them visible under magnification.
trigonal system – An attempt to clarify the rhombohedral class of the hexagonal system, by setting it up as a system with three axes, paralleling the rhombohedral intercepting edges. Some mineralogists divide the hexagonal system into two. The low symmetry portion, the rhombohedral class, is considered the trigonal crystal system.
trilling – A type of twining in which three crystals are intergrown according to regular laws; chrysoberyl trillings are best known to gemologists.
trillion cut – The principles of the brilliant cut applied to triangularly-shaped rough; 44 facets and polished girdle, developed by Louis and Joseph Asscher of Amsterdam.
trimmer capacitor – The electronic regulating device of quartz timepieces, a variable capacitor.
trip – Brownish yellow tourmaline.
triphane – A name given to spodumene by Hatiy in reference to his idea that its cleavage in three directions was equally good, hence “threefold.”
triple A – Diamond grade term sometimes employed by dealers, but of no official standing.
triple cut brilliant – The modern modification of the old single and then double cut brilliants which, toward the end of the 17th Century, began to be cut for brilliance as well as for weight. An additional series of facets, known as the triple cut facets, were placed on the stone.
triple keystone – A pricing key meaning three times dealer cost, used by some suppliers to show dealer cost without disclosing it to public. See KEYSTONE; DELTA.
triple plate – Industry term for silverplate equivalent to 6 Troy ounces of silver for a gross of teaspoons, with an average thickness of 900/1,000,000 of an inch. Formerly also known as heavy or XXX.
triplet – An imitation stone composed of three parts, the top and bottom held together by a colored layer to make a gem “sandwich.”
tripeltine – Emerald triplet.
tripoli – A porous, decomposed siliceous rock which results from the weathering of chert and siliceous limestones. “Rotten stone” may be included in this type of material. Used as abrasive for preparing jewelry work for polishing. The powdered stone is usually mixed with a binder and molded into cakes, for convenience in applying to buffs.
tripping – 1. The action of any escapement with extremely shallow lock; the escape wheel teeth run rapidly past the pallets instead of alternately locking and giving impulse. 2. In a lever escapement, an escape-wheel tooth getting on an impulse-face of pallet stone when impulse is not to be given, caused by faulty safety-action.
Troy weight – System long used for weighing precious metals; the name is derived from Troyes, France, where the system was used prior to its introduction in England in the 15th Century. Its smallest unit, the grain (gn.), is the same in troy, apothecaries and avoirdupois weights. 24 gn. = 1 pennyweight (dwt.); 20 dwt. or 480 gn. = 1 Troy ounce; 437.5 gn. = 1 oz. avoirdupois; 7000 gn. = 1 pound avoirdupois; 15.432 gn. = 1 gram; 12 oz. Troy = 1 pound Troy (Ib. t.) = 240 dwt. = 5,760 gn. See AVOIRDUPOIS; METRIC.
True Star – Misnomer for a cabochon cut glass imitation of a star sapphire, with the star incised in the bottom.
truing – On watch balances, or other wheels, the operation of correcting any irregularity of form that would make the part run untrue in circular motion. Truing a watch balance is a necessary preliminary to poising it, which in turn is necessary to produce good timekeeping in varying positions of the watch while in use. See POISING; TRUING-CALIPERS.
truing calipers – Tool for holding balances or train wheels, while rotating them to test trueness; and for truing them. The two main types are (a) calipers that hold pivots by their ends, for testing only; balances or wheels must be taken out of these calipers to make bends for truing them; (b) calipers that hold pivots by their bases, in which the work is held both for testing, and bending to true it. Tools used for making bends are either truing wrenches, or heavy tweezers.
truing wrench – See TRUING CALIPERS.
trundles – The pins of a lantern pinion.
trunnion – The pivot projection at right angles from the suspension spring block as in some pendulum attachments to their brackets.
tsavorite – A transparent, nearly emerald green variety of grossular garnet found in Tanzania in the mid-Nineteen Sixties and subsequently in Tsavo National Game Preserve in near-by Kenya; termed tsavolite by Europeans, it was christened tsavorite by Tiffany & Co. in 1974. Traces of vanadium are believed to produce the bright green hue; refractive index, 1.744 as compared to emerald’s 1.57; hardness, 7+ as compared to emerald’s 7.
tube cutting jig – An adjustable device used for cutting tubing. The perfectly square ends formed aid in the fit of joints and hinges.
tugtupite – A pink Greenland mineral, related to sodalite and hackmanite, that has been cut in Denmark into some pink cabochons. It is a sodium, beryllium, aluminum chlorosilicate which fluoresces pink and orange (short wave and long-wave UV), found in small quantities at Ilimaussaq, Greenland.
tulip – A gem shape like a flower, with two outward curving points extending from the bell-like corolla. See BELL.
Tully refractometer – A refractometer designed by Bristow J. Tully (1879-1929), with the focal length of the optical system so extended that it is possible to make accurate readings in the second place.
tumbler – 1. A finger on a hub mounted on the end of an arbor, that engages with notches in a rack in mechanism of striking clocks or repeater watches, to move the rack one tooth for each blow struck on bell or gong. 2. Rotating barrel used in polishing method called TUMBLING.
tumbling – Method for polishing large quantities of cheaper grades of jewelry of certain shapes (without sharp cornered features), by rotating them in a power-driven barrel with special polishing agents; the pieces are polished by friction as they “tumble” on each other.
tungsten carbide – Carbonized tungsten, used in powder form as an abrasive, or formed into a solid with a binder, making an exceedingly hard substance for tools for cutting metals, tips for gauges, etc.
Turkey stone – 1. A fine variety of hard oilstone, for final sharpening of steel cutting-tools; also pulverized for use as an abrasive for steel work. 2. Turquoise.
Turkey fat – Local name applied to the yellow stained (from cadmium sulphide) smithsonite from Arkansas, sometimes cut in cabochon gems.
Turk’s head – Brazilian tourmaline crystals with a red tip. See MOOR’S HEAD.
turning – Class of operations for producing work of circular cross-section on a lathe, with cutting tools. See LATHE.
turning graver – Hand-used cutting tool for lathe work, differentiated from gravers used for engraving.
turns – A small dead-center lathe, in which work is rotated by a pulley-collet clamped on it and driven by a hand-bow. Earliest form of watchmakers’ lathe for turning, still used in Europe; now used in U.S.A. only for altering and polishing pivots in adjusting watches. See LATHE.
turntable – A simple form of holder for engraving or other work requiring rotary movement while being cut; essentially a base with a flat table that may be turned on a stem by hand. An elaborate form of turntable is the engravers’ block with various attachments for holding all shapes of work.
turret lathe – A semi-automatic lathe with different cutters set into the swiveling head on the slide rest.
turquoise – (tur-koiz’ or tur-kwoiz’) A hydrous copper aluminum phosphate, always occurring in fine-grained compact masses and often of an attractive blue color. Cut cabochon, sometimes with bits of brown or gray matrix. It is one of the most attractive of the opaque gem-stones, but has only been found once in triclinic crystals at a locality in Virginia and which is of no gem significance. The commonest occurrence is in arid regions, especially in the North American southwest. Much turquoise has been impregnated with blue plastic or soaked and dyed in almond oil or warmed paraffin. Imitations include dyed howlite, molded phosphatic material and glass. Hardness, 5 to 6; specific gravity, 2.6 to 2.9; refractive index, 1.61 to 1.65. See AGAPHITE; ALESSANDRINE TURQUOISE; BONE TURQUOISE; CALAITE; CALLAINITE; CHAL-CHIHUITL; CHINESE TURQUOISE; COBWEB TURQUOISE; EGYPTIAN TURQUOISE; FIROZEH NAKIS; JOHNITE; SYNTHETIC TURQUOISE.
turquoise matrix – Name given to the cut mixtures of turquoise with its associated rocks; usually more attractive and interesting than the pure blue turquoise.
turtle back – Most commonly the harlequin-like patches of fibrous green cabochon cut chlorastrolite. Also applied to turquoise and variscite matrix.
turtle back pearl – Rounded oval-shaped, high domed blister pearl.
tuxedo chain – A chain for carrying a pocket watch, one end attached to a clasp to fasten to a belt or trousers-top, the other end with a swivel or spring-ring to attach to bow of watch.
tuxtlite – (tush’tlite) Name proposed by H.S. Washington for the midway, 1 to 1, soda to magnesia member of the pyroxene series of jadeite found in Mexico, and constituting the important constituent of mayaite. The presence of the magnesium silicate, or diopside, molecule, renders this jadeite distinct from the Burmese jadeite, which contains very little magnesia. See MAYAITE; DIOPSIDE.
tweezers – Tools for quick handling of small pieces in watch and jewelry work; differing from pliers in having jaws on a pair of springs, fastened together at one end, instead of on levers pivoted to turn on each other; the springs keep the jaws opened except when closed by the fingers.
Twentieth Century cut – A modified brilliant cut with 80 or 86 facets said to have been invented by Adolph Adler and first shown at the Antwerp World’s Fair in 1885.
24 Karat Club of the City of New York – Leading social organization of the American jewelry, industry; founded in 1902; its 200 active members are engaged in the manufacture of: wholesaling of jewelry; annual dinner in January at Waldorf-Astoria hotel in New York is attended by members and 1300 guests. Club: of similar name have been founded in other: cities, including Dallas, Los Angeles and Atlanta.
twin line – An indication on a polished surface o a change in orientation as a result of twinning; in a stone (see TWINNING); in the middle of a facet, they often reveal themselves a: straight lines across a polished surface.
twinning – An intergrowth of two or more crystals, or parts of crystals in reversed relation ship to each other, in accordance with some mathematical law. It is caused by an actual reversal of atomic positions in the crystal lattice, and the frequency with which it occur: depends upon the ease with which such reversals can take place in the lattice structure Some minerals never twin; others frequently Of the latter some may twin only in a single direction, others may twin according to several different laws. The flat triangular diamonds twinned on the octahedron face ac cording to what is called the spinel law are best known to the gemologist. See MACLES
twist drill – A tool for drilling holes, made by milling round-bottomed grooves spirally on a steel rod, then forming two cutting lips at the end and hardening the steel. In watch and clod work, twist drills are in general used for large: holes, and flat drills for smaller holes. See DRILL; FLAT DRILL.
two point diamonds – Diamonds cut with the table parallel to a dodecahedron direction; the grain runs in a single direction across the face, and may make a distinct ridge. Also, diamonds weighing 0.02 ct.
tympania – The ancient name for hemispherical pearls grown against the shell of the oyster, and often still attached.
Type I diamonds – Said to comprise 99.1% of all gem diamonds, they contain an abundance of nitrogen atoms, are non-conductors of electricity due to the presence of aluminum atoms, absorb ultra-violet from 3300 A. In Type J-a diamonds, the nitrogen atoms are aligned in tiny platelets that absorb ultraviolet, beyond the visible blue end of the spectrum, thus permitting colorless stones. In Type I-b stones, which are perhaps 0.1% of all Type I stones, the nitrogen atoms are dispersed and absorb light in the blue end of the spectrum, resulting in yellowish stones. Nearly all diamonds are thought to intermix materials, their classification as a or b being in accordance with which material is preponderant.
Type II diamonds – A small proportion of natural diamonds belong to this type; they contain little or no nitrogen; are better heat-conductors than the Type I stones; are transparent to ultra-violet to about 2250 A. Type Il-a stones, containing few if any impurities, are usually colorless and relatively formless; they include the huge diamonds such as the Cullinan and Star of Sierra Leone. Type Il-b stones, thought to be about 0.1% of all Type II stones, contain dispersed aluminum atoms; are semi-conductors of electricity; they are of use in p-type transistors; are photoconductive to gamma rays; and can measure temperature from -200° to +600° centigrade. All natural blue diamonds, including the Hope, are Type Il-b.
type specimen – In scientific terminology, the specimen on which the original description of a species was based, an illustrated specimen. Some of the gems described and illustrated in Gemstones of North America by Dr. George Frederick Kunz and now in the Morgan Collection in the American Museum of Natural History, New York, could be considered type specimens. Because of the associations, they are considered as having more value than almost identical, but unpublicized, stones.
Ultralite – Trade-marked name for a red-violet synthetic sapphire.
ultrasonic cleaner – 1. A cleansing agent dissolved in a solution and vibrated at frequencies higher than those audible to human ear, above 20,000 per second. At such vibrations, foreign matter and dirt are dislodged from articles, such as jewelry and timepieces, that are being cleaned. 2. Also, used for the removal of investment from castings.
ultraviolet or UV – Light with wave-lengths above the visible spectrum which can stimulate a response in the visible spectrum in some materials, including gemstones, which is known as fluorescence. A persistant glow after such an exposure is known as phosphorescence. Fluorescence and phosphorescence can also be stimulated by x-rays (even shorter wave-length rays than those of the UV). UV is subdivided into long-wave and short-wave ultraviolet. Responses often differ in the two types of light. Short-wave-length UV is harder to obtain; it takes an iron arc or a quartz mercury tube. Long-wave-length UV is easier; being closer to the visible spectrum it can be produced by an intense filament bulb (“black lights”) enclosed in filter glass material, with an argon bulb, or with a filtered fluorescent tube. For many uses, the observation of synthetic emeralds or “Premier” diamonds, longwave-length UV lights are adequate.
umbrella chuck – A split, step chuck in convex form whose largest diameter and underside are hollowed out to be spread outward by the headstock spindle when the draw-bar is tightened. Used for holding rings and small bezels for lathe turning.
unakite – (yoo’na-kite) Name applied to a stone infrequently cut by amateur lapidaries composed of reddish feldspar, green epidote and some mica. It may be considered an altered granite.
unbreakable crystals – Watch crystals made of transparent plastic materials tougher than glass, that withstand blows without breaking.
unctuosity – The property of certain applied substances to reduce friction. The oily quality of a substance.
uncut balance – A solid or bimetallic balance whose rims have not been split or cut.
under-compensated – The condition of a watch when it gains time in low temperature and loses time in higher temperature; the compensating action of the balance is insufficient and must be corrected by moving screws nearer the cut or free ends of balance-rim segments.
undercut – 1. A V-shaped groove turned at the base of a pivot to prevent surplus oil spreading from a bearing on to a staff or pinion. 2. The space turned out on balance shoulder of a staff to form a rivet for staking staff to balance.
undercutting – Reducing weight of balance screws, for poising or regulating, by removing metal from bottom of head with a hollow end-mill.
underhand – English term to denote operation of grinding or polishing flat metal, done by rubbing the work on a flat bench-lap.
undersprung – Location of hairspring, usually in a full-plate watch, in which the spring is colleted to the balance staff under the balance-arm instead of above it.
undetached – A term used to denote any variety of factional escapement. See FRICTIONAL ESCAPEMENT.
uniaxial double refraction – See BIAXIAL. Uniaxial minerals include those crystallizing in the tetragonal or hexagonal system and which consequently have but a single direction in which there is no double refraction. This direction is parallel to the c, or unequal, crystal axis.
Unio – (yoo’nee-o) The family to which the freshwater pearl-bearing mussels belong.
unionite – Pink zoisite.
unit cluster setting – A plate of any geometrical shape, either flat or domed, drilled to accommodate a given number of melee.
unit jewelry – Jewelry made of simple wire forms in various shapes and sizes, combined to form a pleasing design.
universal face-plate – An attachment mounted on a chuck to be held in spindle of regular watchmakers’ lathe for holding watch plates, etc., on which eccentric locations are required for doing recessing, bushing, drilling, uprighting, etc. See LATHE; UPRIGHTING.
universal lathe – A special lathe of European design, with a universal face-plate its only work-holding feature; driven by a handwheel or crank, with gearing to multiply speed to the spindle. See UNIVERSAL FACE-PLATE.
unlocking – In an escapement, the withdrawal of a pallet or other form of mechanical obstacle from in front of an escape-wheel tooth, to allow the function called “lift” (for giving the balance an impulse) to be performed by the tooth.
unlocking resistance – The force in escapement action that opposes effort of the balance to unlock the escape-wheel at each beat; caused in deadbeat escapements by friction of tooth on pallet and in detached escapements by the latter, plus the force of draw. See DEAD-BEAT; DRAW; ESCAPEMENT; UNLOCKING.
unripe diamonds – Missnomer for gray or colorless zircon.
unripe pearls – A common term for poor quality pearls; fine pearls with a good orient being known as “ripe.”
unripe ruby – Misnomer for red zircon.
up-and-down indicator – A small extra dial and hand on dial of timepiece, with mechanism, to indicate how many hours a timepiece has run since it was last wound. It is always on marine chronometers; occasionally on fine watches.
upper girdle facets – The 16 triangular facets immediately above the girdle of a round brilliant cut stone. Also called upper-break facets, upper-half facets, top-break facets, top-half facets. See GIRDLE FACETS.
upper jewel – The one of a pair of these parts that is nearest the observer as looked at with a watchcase opened; the one that is in the balance cock; trainhole jewels, etc., in the top-plate.
uprighting – Locating and doing a job of drilling, bushing or jeweling for a bearing for a pivot so that the center of the bearing will be exactly opposite the center of bearing for the other pivot; so that the pivoted arbor will stand perpendicular to the planes of the plates holding the bearings.
Ural chrysolite, emerald, or olivine – All misleading terms for demantoid garnet, a fine gem which can stand on its own feet.
Uralian sapphire – Blue tourmaline.
Uruguayan agate and amethyst – Material from the region along the border of Rio Grande do Sul, Brazil and Uruguay. It shows the same characteristics as the south Brazilian rough, the agate occurring in large masses of a grayish color, the amethysts mostly small and strongly color-banded.
Utah turquoise – Variscite.
utahlite – Variscite from Tooele County, Utah, where it occurs in green-cored nodules surrounded by alteration rims of other minerals, none of which have gem significance except wardite.
“Ut tensio sic vis.” – Latin statement of theory of action of balance spring, as expressed by Robert Hooke, in claiming its discovery. A translation is: “As the tension is, so is the force”— of a spring.
uvarovite – (you-va’ro-vite) A deep green chromium garnet, usually associated with chromium deposits and of no gem significance, despite its usual inclusion as a gemstone variety in texts. Its crystals are usually small, rather brittle, and generally opaque. Large crystals have been found in Outokumpu, Finland, but they are shattered and cannot be cut. The green garnets of the trade are mainly green andradite garnets, demantoid, or green grossular garnets. An occurrence in Quebec asbestos mines, where the grossulars seem to have a black and then green core, suggests that there may be a transition of uvarovite into grossular and that the coloring material of both garnet varieties is chromium.
uvite – Name proposed for the calcium end member of a series in the tourmaline classification, which is thus transformed into a group, as has been the case with garnet.
vabanite – A brownish red yellow-flecked banded jasper from California.
vacuum case – Wrist watch in which the movement is cased in a vacuum.
vacuum casting – Finely detailed castings are produced by investing wax patterns in a flask the cylinder of which is perforated with closely-spaced holes about 3/8″ diameter. After the wax is burned out, the entire flask is placed in an airtight container, molten metal poured into the opening at the top, and a vacuum generated within the container. The vacuum, acting through the porous investment, draws the molten metal into the mold, forming dense and sharply-defined castings.
vacuum coating – A process whereby a coating metal is deposited on a substance by volatilization in a vacuum. Plastic articles thus coated have a metallic finish microscopic in thickness. Inexpensive metal castings are vacuum coated with aluminum and dyed to a gold color.
vacuum machine – A device for removing air from freshly prepared investment by means of a vacuum beneath a bell jar. Air bubbles, if left, would produce spheres of metal on the casting.
Vallum diamond – Misnomer for a rock crystal cut in Vellum in the Tanjore District, Madras, India.
valve, electronic – A vacuum tube, diode, transistor, etc., which allows current to flow in a controlled direction.
vane – One of the planes standing out from the spindle of balance arbor in a verge escapement, that acts as a pallet in the verge escapement. See VERGE ESCAPEMENT.
variation – The amount of difference in rates of a timepiece under different conditions; for example, when compared as running in a higher and a lower temperature.
variegated gold – Decoration on jewelry, etc., in different colors of gold alloys.
variety – In gemology or mineralogy a type of a certain mineral given a special name because of its color, or because of some other characteristic. Rubies and sapphires are varieties of corundum; citrine, cairngorm and amethyst are varieties of quartz.
variolite – Dark green orthoclase with light-colored globules.
variscite – A rather uncommon hydrous aluminum phosphate. Found in green masses, colored by iron and chromium, at several localities in the west, most notably at Lucin, Utah. Cabochon stones cut from this material, sometimes with eyes of wardite or other alteration products, make attractive stones. Hardness, 5; specific gravity, 2.52 to 2.60.
vashegyite – An aluminum phosphate, close to variscite in manner of occurrence and appearance. An occurrence near Manhattan, Nye County, Nevada, has been worked in a small way for gem stones. See TRAINITE.
V-block – A block with a triangular groove into which is rested a cylindrical object for drilling or other manipulation.
vein – In mining terminology, an irregular tabular body cutting rocks and composed of a different sort of mineral material, presumably deposited from solutions.
venting – In making molds for casting jewelry, making small holes in the sand to allow escape of gas and air during pouring the metal.
Venus’ ear – Abalone shell.
verd antique – 1. A brownish-green finish on bronze wares resembling the patina produced by age; made by immersing bronze in a sulphate of copper and sal ammoniac solution. 2. A decorative marble composed largely of serpentine with scattered veins and patches of white calcite or dolomite.
verde de Corsica – A green decorative stone found on the Island of Corsica, composed of diallage and labradorite and showing a metallic schiller.
verdigris – (vur’duh-greese) Oxidation on surfaces of wares containing copper; usually of green color.
verdite – A green jade substitute, composed mainly of the green chromium mica, fuchsite and clay. It occurs in the Barberton District of the Transvaal, South Africa. Figurines of this material are among the most popular South African tourist souvenirs.
verge – The part of a verge escapement that comprises the balance staff and vanes or pallets, all formed out of one piece of steel.
verge escapement – The earliest form of escapement for timepieces; used in clocks from about 1300, and in watches from about 1500, and mostly displaced by other escapements by about 1800. Essentially it consists of an escape wheel running in a vertical plane, with sawlike teeth which work against steel plates superimposed on the balance-arbor and forming the pallets. This escapement was simple and sturdy but had the faults that it was a frictional escapement and had extremely great recoil in action. It is entirely obsolete today. See ESCAPEMENTS.
vermeil – (vehr-may’) 1. Metallurgy. Originally, a thin paste of niter, alum, sulfate of iron, red ocher and other coloring matter used to produce a fine red or yellow color on mercury-gilded objects. The gilt object was coated with such a mixture, heated and washed. See ORMOLU; MERCURY-GILDING, b. After 1858, silver gilt, silver bronze, c. Heavy gold electroplate over sterling silver, following the purchase by Mrs. John F. Kennedy of such a flatware service for the White House from Tiffany & Co., or a substantial layer of karat gold mechanically applied over sterling silver. The marking “sterling/vermeil” or “vermeil/ sterling” was proposed in 1974. 2. Gemology. A misleading term applied to orange-red spinels, zircons and garnets.
vermicelli – 1. Kind of decoration on jewelry, etc., consisting of units of wire, curved strips, small beads, etc., soldered in designs to a plain-surface background; also called Etruscan work. 2. Engraved decoration. A surface covered completely with small cuts in form of scrolls, curves, etc.
vernier – A device for reading fractions of a division on the scale of a linear measuring instrument; an auxiliary scale sliding against the main scale; also used to mean the complete instrument. See BOLEY GAUGE.
verstel – A face or the fully brillianteered bezel of a cut diamond, including the adjoining halves.
vertical escapement – The verge escapement; so called because the escape wheel runs in a plane perpendicular to the plates of a watch and to differentiate from the “horizontal” or cylinder escapement, in which the escape wheel runs in a plane parallel to the watch plates. See VERGE ESCAPEMENT.
vertical positions – In position adjusting, positions in which the watch runs as if standing on its edge; pendant up, pendant right, pendant left or pendant down. Differentiates from horizontal positions of dial up and dial down. Sometimes called on-edge positions.
very slightly included – Abbreviated VS, a diamond clarity grade between very very slightly included (VVS) and slightly included (SI). It designates diamonds with small internal or surface blemishes that are readily visible under 10-power magnification but cannot be seen by the unaided eye. The term very slightly included is preferred to the earlier expression very slightly imperfect. Sub-grades VS1 and VS2 are used according to the number, location and size of blemishes.
very small inclusions – A Scan D.N. clarity grade. See VERY SLIGHTLY INCLUDED.
very, very slightly included – Abbreviated WS, a diamond clarity grade between flawless (F) or internally flawless and very slightly included (VS). It describes diamonds with minute internal or surface blemishes that are difficult for a trained eye to observe under 10-power magnification. The term very, very slightly included is preferred to the earlier expression, very, very slightly imperfect. Sub-grades and VVS2 are used, according to the incidence of small naturals, nicks, scratches, pinpoints, slight bearding or other minor fault.
very, very small inclusions – A Scan. D.N. clarity grade. See VERY, VERY SLIGHTLY INCLUDED.
Vesuvian garnet – A white mineral, leucite, potassium aluminum silicate, which crystallizes at Vesuvius in well-formed crystals resembling garnets.
vesuvianite – An interesting hydrous, calcium, aluminum, and silica mineral which forms usually in rocks which have been subjected to metamorphism by magna intrusions. The original occurrence was at Mt. Vesuvius, where it formed in blocks of the original limestone crust through which the lava came, while they were immersed in the magna, deep in the roots of the volcano. It is green, yellow, brown, reddish, bluish and colorless. It crystallizes in the tetragonal system, commonly in square prisms, less often in pseudo-octahedrons. Refractive index ranges from 1.70 to 1.72; specific gravity, 3.35-3.45; hardness 6Vz. Its varieties include CALIFORNITE, CYPRINE and XANTHITE. It is also known as idocrase.
vibrating – Term used in watch material trade, meaning the operation of trying different hairsprings from a stock of them, each temporarily attached to a watch balance, until one is found with which the balance will beat the number of vibrations per hour to match the train of the timepiece. See TRAIN.
vibrator – 1. Instrument for testing hairsprings, in matching them to watch balances, comprising a standard balance assembly and an adjustable clamp to hold the spring being tested while attached to balance being matched, with which different springs may be quickly tried until one is found with vibration-rate the same as that of the standard balance. 2. Jewelry. A hand-held electrical device with rapidly vibrating tip of steel or carbide, used to inscribe lettering or designs on metal or glass.
Vickers hardness test – A test for metals in which a diamond pyramid is pressed into the metal by a load of 5,120 kilograms.
Vienna lime – A purified variety of lime, originally produced in Austria, used in combination with alcohol on a wood lap for obtaining a quick polish on steel watch parts. Its action is chemical more than mechanically abrasive and the polish is inferior to that produced by abrasives like rouge or diamantine, being comparatively superficial and white.
Vienna turquoise – Misnomer for a blue masse imitation of turquoise erroneously called synthetic turquoise because it has almost the same composition, hardness, color, gravity, fracture and appearance. It is chemically precipitated, dyed with a copper salt and pressed into a solid mass with very much the appearance of the genuine stone. Without destruction of the stone it is difficult to distinguish from the genuine, but little if any has been manufactured in recent years. See SYNTHETIC TURQUOISE.
vinegar spinel – Reddish to yellow spinel.
violane – A violet, opaque variety of pyroxene found in Italy and sometimes cut into attractive cabochon gems. Though little exploited, it is reported that deposits at Praborna, near S. Marcello in the Val d’Aosta, could produce a considerable quantity of attractive stones.
violet ruby or sapphire – Amethyst-colored corundum.
Violite – Reported to be a trade-marked name for synthetic violet-colored corundum.
virgule – A watch escapement of French invention (about 1750) that was in some respects better than the cylinder escapement, being less frictional in action. Used by several eminent makers until the difficulty of keeping oil on the pallets caused its abandonment. Also called the “hook” or “comma” escapement, from the form of its pallets.
viridine – A green manganese pigmented variety of andalusite, rarely more than translucent and consequently seldom of gem value, but a potentially attractive stone for its fine bright grass-green hue and strong dichroism (green and yellow).
viscoloid – A variety of celluloid.
vise – A device having two jaws, usually closing with a screw, for holding work while cutting or filing. Vise is normally attached to a firm bench.
visible lapper – A beveled lapping wheel with radiating slits. Without removing work from wheel, the lapping operation is viewed through the rotating slits. See SPLIT LAP.
visible pallets – Pallet stones set in slots cut vertically in the pallet yoke; in view from above. Differentiated from stones set in slots cut horizontally in yoke which thus cannot be seen except viewed edge-wise of the pallet.
vitreous – A luster term in mineralogy, meaning glassy, and the proper descriptive term for the appearance of many of the gemstones. See ADAMANTINE and RESINOUS.
vivianite – A hydrous iron phosphate, interesting to jewelers because it is the blue coloring matter of odontolite, the so-called “bone turquoise.”
vixen file – A file with curved single cuts for soft metals or for smoothing work rotated in a lathe.
volcanic glass – Obsidian.
voltmeter – Instrument used in electroplating to regulate the current strength for the bath.
volute – Horology. The flat spiral form that hairsprings have prior to bending up the outer coil to make Breguet or overcoiled springs. Also as used flat, without overcoiling in very thin modern watches, and as used in all watches before the invention of overcoiled springs.
vorobyevite – A Russian term for pink beryl, the USSR equivalent of morganite.
VS – Abbreviation used in diamond clarity grading for very slightly included, very small inclusions, or very slightly imperfect. Its sub-grades are VS1 and VS2.
vulcanite – Hard rubber used for pulleys on watchmakers lathes or handles on tools. Formerly used as substitute for jet for mourning jewelry.
vulcanizer – A heated press used to vulcanize rubber molds and to make metal molds for the production of wax patterns.
VVS – Abbreviation in diamond grading for very, very slightly included, very, very small inclusions, or very, very slightly imperfectly sub-grades are VVS1 and VVS2.