Thursday, June 6, 2013

Ruby and Sapphire

Corundum is a crystalline rock-forming mineral. It is the third hardest mineral known with diamond and moissanite being the only minerals with a greater hardness. It serves as the index mineral with a hardness of nine on the Mohs Hardness Scale. It is used as gemstones varieties, Rubies and sapphires that are famous throughout the world.