Watch Crystals

The crystal is the transparent protective covering that fits over the watch face, and is held in place by the bezel. It's exposed to all manner of shocks and blows, so it should be as hard as possible. Softer materials scratch and break easily, making the watch less attractive and possibly unreadable. Worse, they could shatter and damage the watch beyond repair.

A crystal can be made from any clear material, from plastic to synthetic sapphire - the hardest and most expensive crystal available. The chart below shows popular crystal types and their relative hardness.