What is sapphire glass?

Sapphire glass has a value of 9 on the Mohs scale and is the second hardest transparent natural substance next to diamonds. This material is considerably more scratch-proof than hardened mineral glass and gets used in optical, technical and medical components, watch glass or occasionally as an optical window or cover.

Sapphire glass is produced from high-purity alumina. The purer the alumina, the harder the sapphire glass. Actually, the term „glass“ is not correct, as this, in contrast to glass, disposes of a crystalline structure and not of an amorphous (glass-like) molecular structure, such as soda-lime glass.