ruby

Gemstone in the corundum family. Ranges from deep pink to blood red to purple-red. Birthstone for July. Mined primarily in Sri Lanka, Madagascar, Myanmar (formerly Burma), Afghanistan, Pakistan, Vietnam, Australia and India. The gem is difficult to find without internal flaws and in deep color. The element chromium is responsible for the red color. Heat treatment is very common in ruby (as in all corundums). Ruby may be any color of red depending on the chromium and iron content of the stone. Sometimes the stones display a 6-rayed star effect when cut as cabochon (dome-shaped) stones. It is also very, very difficult to find in larger sizes. In 1988, a 15.97-carat unheated Burmese ruby known as the Mogok Ruby was sold by Sotheby's auction house in New York for $3,630,000.