Watch Terminology Dictionary

A crystal made of sapphire crystal. It is stronger than plastic or tempered glass crystals and has been used in many watches since the 1980s. The first recorded example of its use was Omega's waterproof watch, the Marine (1932). Because it is extremely hard, it was considered difficult to process it into anything other than a flat surface, but since the 1990s, some luxury watches have had domed sapphire crystal. It is said that the manufacturing costs of flat sapphire crystal differ from those of domed crystal by five to ten times.