Rubies, like sapphires, are a variety of the mineral corundum, which is known for its remarkably rich color. The Eminent Star ruby, the largest known, weighs 6,465 carats, or almost three pounds. Class: precious Origin of Name: from the Latin ruber (red) Color: red, orange-red, purple-red Chemical Composition: aluminum oxide Crystal System: trigonal Hardness: 9 Specific Gravity: 3.96-4.05 Geographic Origins: Burma, Thailand, Cambodia, Kenya, Tanzania, Zimbabwe Next Photo: ©International Colored Gemstone Association The Science Behind the Sparkle | Diamonds in the Sky A Primer of Gemstones | See Inside a Diamond Resources | Transcript | Site Map | Diamond Deception Home Editor's Picks | Previous Sites | Join Us/E-mail | TV/Web Schedule About NOVA | Teachers | Site Map | Shop | Jobs | Search | To print PBS Online | NOVA Online | WGBH © | Updated November 2000