Sapphire refers to gem varieties of the mineral corundum, an aluminium oxide (Al2O3), when it's a color other than red. Sapphire can be found naturally or manufactured in large crystal boules. Because of its remarkable hardness sapphire is used in many applications, including infrared optical components, watch crystals, high-durability windows, and wafers for the deposition of semiconductors, such as GaN nanorods. The mineral corundum consists of pure aluminium oxide. Trace amounts of other el… (More on Sapphire)