Hardness of Corundum, Hardness of Ruby and Sapphire Corundum is 9 on Mohs’ scale. Hardness of Ruby and sapphire may be brittle and should be carefully handled. The fracture varies from uneven to conchoidal. There is no cleavage. Parting, from exsolved bohmite, may occur parallel to the basal plane or rhombohedral faces.
Hardness of Ruby and Sapphire

Hardness of Ruby and Sapphire