Red corundums are rubies. Blue corundums are sapphires. Trace elements produce their colors.

Most people don’t realize that ruby and sapphire are both gems of the mineral corundum. Both of these gemstones have the same chemical composition and the same mineral structure. Trace amounts of impurities determine if a gem corundum will be a brilliant red ruby or a beautiful blue sapphire. It is surprising that “impurities” can produce such wonderful results!

Red and blue are just two of the many colors found in gem corundums. Trace amounts of other elements can produce brilliant yellow, orange, green, and purple gems. Red corundums are known as “rubies,” blue corundums are known as “sapphires,” and corundums of any other color are known as “fancy sapphires.” Impurities cause corundum to occur in a spectrum of colors, and when it is completely free of color-causing impurities, it is a colorless gem known as “white sapphire.”