What does the crystal of a watch refer to?
The crystal is the cover over the face of the watch. There are three different types commonly used in watches; acrylic, mineral, and sapphire. Acrylic crystal, a plastic, is inexpensive and shallow scratches can be buffed out. Mineral crystal is comprised of several elements that are heat treated to create unusual hardness that aids in resisting scratches. Sapphire crystal is the most expensive and durable, approximately three times harder than mineral crystals and 20 times harder than acrylic crystals. A non-reflective coating on some styles prevents glare.
