Sapphire is a precious gemstone, a variety of the mineral corundum, an aluminium oxide (α-Al2O3). It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors; "parti sapphires" show two or more colors.
Significant sapphire deposits are found in Eastern Australia, Thailand, Sri Lanka, China (Shandong), Madagascar, East Africa, and in North America in a few locations, mostly in Montana. Sapphires and rubies are often found in the same geological setting. (Wikipedia)