sap·phire | ˈsa-ˌfī(-ə)r
A member of the corundum family which come in a variety of colors ranging from white to orange to green to pink to blue to purple
One of the four precious gemstones, alongside diamonds, rubies, and emeralds. If a corundum gemstone is red, it is a ruby, but any other colors are properly referred to as sapphires.
Blue sapphire is the birthstone for September.