Corundum Gem Varieties

Corundum [1344-28-1] with the chemical formula Aip, and the relative molar mass of 101.96127 is named after the Hindi, kurund, or the Tamil, kurundam. Corundum with a trigonal space lattice is the second hardest mineral on the Mohs scale just after diamond. The well-known gem varieties are the blood-red ruby while all other colors are named sapphire (e.g., pink sapphire, yellow sapphire) despite it is commonly used to denote the blue 

Colorless Violet-blue to lighter Intense blood-red to lighter 

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