Sapphire is a precious gemstone variety of the mineral corundum. It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colours; "parti sapphires" show two or more colours. Red corundum stones also occur, and are referred to as a Ruby. Pink coloured corundum may be either classified as ruby or sapphire depending on locale. Commonly, natural sapphires are cut and polished into gemstones and worn in jewellery.