Most people are familiar with corundum; however, very few people know it by its mineral name – instead they know it by the names “ruby” and “sapphire.” A gemstone-quality specimen of corundum with a deep red color is known as a “ruby.” A gemstone-quality corundum with a blue color is called a “sapphire.” Colorless corundum is known as “white sapphire.” Corundum of any other color is known as “fancy sapphire.”