Sapphire refers to gem varieties of the mineral corundum, an aluminium oxide (α-Al2O3), when it's a color other than red, in which case the gem would instead be a ruby. Trace amounts of other elements such as iron, titanium, or chromium can give corundum blue, yellow, pink, purple, orange, or greenish color. Pink-orange corundum are also sapphires, but are instead called padparadscha. Because it's a gemstone, sapphire's commonly worn as jewelry. Sapphire can be found naturally, or manufact… (More on Sapphire)