Sapphire, the September birthstone, has been popular since the Middle Ages and according to folklore, protects your loved ones from envy and harm. Medieval clergy wore sapphires to symbolize heaven, while commoners thought the gem attracted heavenly blessings. Blue sapphires range from very light to very dark green or violet-blue, as well as various shades of pure blue. The most prized colors are a medium to medium dark blue or slightly violet-blue. Sapphire is a variety of the gem species corundum and occurs in all colors of the  rainbow.  Pink, purple, green, orange or yellow corundum are known by their color (pink sapphire, green sapphire).