K1 mineral glass is a hardened mineral glass which is much harder than normal mineral glass. The glass is made by grinding and not by heating.K1 mineral glass is a hardened mineral glass which is much harder than normal mineral glass. The glass is made by grinding and not by heating.
The following comparison helps with orientation:
Vicker hardness test : sapphire - around 1900, K1 - around 700, mineral glass - around 380
Mohs hardness scale (from 0-10, the hardness of diamond is 10) : sapphire - around 9, K1 - around 6, mineral glass - around 4.