Next to ruby and the rare red diamond, spinel is the most expensive of all red gems, commanding prices as high as $2,000 per carat for stones above one carat in weight. (One carat equals one-fifth of a gram.)

Class: semiprecious
Origin of Name: probably from the Latin spina (thorn)
Color: red, orange, brown, green, blue, violet, clear
Chemical Composition: magnesium aluminum oxide
Crystal System: cubic
Hardness: 8
Specific Gravity: 3.58-4.06
Geographic Origins: Sri Lanka, Burma, Brazil

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Photo: ©International Colored Gemstone Association

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