Sapphire Sapphire is a high-purity and high-density, single-crystalline form of aluminum oxide, which may contain chromia, titania, yttria, or other dopants. Sapphire is usually transparent or ...

Examples include calcium aluminate, sapphire, and alumina-zirconia. Calcium aluminate (CaAlO 3) is an aluminate ceramic used in refractory cements and shapes, as well as synthetic slag additions for ...