- Measure the seat diameter, not the outside of the bezel. Sapphire is usually a press fit into a tension ring or gasket.
- Flat crystals suit tool and dress watches; domed and double-domed give a vintage look. Watch for internal AR coating — it changes the reflection colour under light.
- Acrylic (Hesalite) can be sanded and polished to remove scratches; sapphire cannot — only replaced.
- Always fit a new gasket when replacing a crystal, and pressure-test before the watch goes anywhere near water.
Cases, Crystals & Water Resistance
Crystal Fitting Basics
Last updated 16 Sep 2026
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