Zircon resembles diamond in its luster and fire, yet it has a tendency to chip out at the facet junctions over the years, so it not prized as highly. (Cubic zirconia, a well-known diamond simulant, is an altered form of the mineral baddeleyite, whose chemical composition is zirconium oxide.) Class: semiprecious Origin of Name: from the word zargoon, meaning vermilion in Arabic or golden-colored in Persian Color: vermilion, yellow, green, brown, blue, clear Chemical Composition: zirconium silicate Crystal System: tetragonal Hardness: 7.5 Specific Gravity: 4.6-4.7 Geographic Origins: Burma, Sri Lanka, Cambodia, Vietnam 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