Glossary

Corundum is a crystalline form of aluminium oxide typically containing traces of iron, titanium, vanadium, and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. In watchmaking, corundum is used to create the front and back glass to protect the dial or various parts of the watch from damage and scratches, as it is one of the hardest materials after diamond in terms of hardness.

Additionally, corundum exhibits high chemical resistance and good transparency, making it an ideal material for glass manufacturing in watches.