In this post, we will show you how to find the measurement for a round glass watch crystal, so you know what size to look for if you have to order a replacement.
Whether or not you currently have your old crystal, this video will show you how to get the right measurement.
The only tools you will need for this are a measuring gauge and a cleaning cloth.
The first thing you will need to do is remove the existing crystal from your watch. For a step-by-step guide, check out our how-to video on removing watch crystals.
Measuring an Existing Crystal
If you already have a crystal on hand the process is simple: Just measure the diameter of the crystal to obtain the proper size.
A digital micrometer is suggested as the results are accurate and easy to read.
Measure in two to three places to confirm the size and round your measurement to the nearest one hundredth of a millimeter (0.01mm)
Measuring the Bezel if Your Crystal is Missing
If the crystal is broken or missing, you can measure the inside of the the bezel. You will need a caliper with an inside measuring jaw to do this.
There is a “Step” ledge on the inside of the bezel where the crystal and gasket will sit. The inside of the wall above this ledge is what you will measure.
Insert the caliper into the step and measure in two to three different places to ensure that you have an accurate measurement. Round to the nearest 1/100 of a millimeter (0.01)
Measuring the Bezel With a Gasket
If the watch already has a gasket that is in good condition, you can measure it in the same way that you measured the bezel. Just be aware that gaskets sometimes have a slight ledge where the crystal sits.
Again, take careful measurements in a few different locations, and round to the nearest 1/100 of a millimeter (0.01).
Understanding Your Measurement
When ordering crystals to fit a gasket, order a size that’s one-tenth of a millimeter larger than the gasket measurement in order to get the proper fit. These crystals are usually used on waterproof watches, and they usually require a press in order to set the crystal.
In this case, since the gasket measurement was 29.4mm, you would order a round crystal with a diameter of 29.5mm
It’s important to not that round crystals come in a number of different styles. If you have the original crystal, you can easily match up the style, but if the crystal is missing, you can choose from our selection of thin, thick, domed and magnifier glass crystals.
The thickness of the crystal can be measured using your caliper.
Ordering the Replacement Crystal
Once you have the right measurement, you can order your replacement crystal at Esslinger-dot-com.
Most crystals come in 0.1 mm size increments, but some styles only come in 0.5 mm increments.
To learn more about watch repair or how to replace your watch crystal, check out other posts on our blog or videos on our YouTube channel!