A Remarkable Corundum (Sapphire) Crystal A Remarkable Corundum (Sapphire) Crystal
Mineral Cabinet

Smithsonian Gem & Mineral Collection

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A Remarkable Corundum (Sapphire) Crystal
 
Gem corundum is found in almost every conceivable color, all called sapphire unless it is red, which is ruby. Corundum is second only to diamond in hardness. This is a remarkable uncut crystal from the Gem and Mineral Collection of the Smithsonian's National Museum of Natural History.
Last modified 2026-08-09 MZ Smithsonian photos by Dane A. Penland
Copyright 1992 Smithsonian Institution 		A Remarkable Corundum (Sapphire) Crystal