If you are only slightly trimming a watch crystal, the process usually requires less expensive tools and usually can be done in a few minutes. Cutting down the size or shape of glass crystals and making significant modifications requires more specialized equipment. The same methods explained here can be used on flat, round, domed, fancy, side walled, and military curved crystals. After you have cut your glass watch crystal down, you can learn how to polish a glass crystal here.
Determine how much you need to change the crystal, particularly noting which sides you need to trim. Once you know which sections need to be trimmed and adjusted, hold the crystal firmly in your non-dominant hand and lubricate the side of the crystal you will start on with a small amount of water.
Take your diamond file and using light pressure carefully begin to file back and forth on the edge of the crystal that needs to be trimmed. Hold the file at a ninety degree angle to the crystal while you work.
Keep the crystal and file lubricated with water to avoid chipping and damaging the crystal. It’s a good idea to stop and check your progress every time you want to re-lubricate your work area. Note: if your crystal is curved, slowly turn the crystal while you file to evenly trim the surfaces.
Once the crystal is the shape and size you need, you can insert it into the watch case. If you want to learn more about watch or jewelry repair, you can check out our Learning Center today.