A red transparent gemstone composed of corundum (aluminum oxide). Rubies range in color from a deep rose red to a pale pink due to small amounts of chromium impurities. They are primarily found in Myanmar (formerly Burma), Kashmir, India, Sri Lanka, Thailand, Zimbabwe, Tanzania, Kenya, Madagascar and the U.S.(North Carolina). Rubies were rarely used in antiquity, probably because of their rarity and extreme hardness. A large clear ruby is more valuable than a diamond of equivalent size. Synthetic rubies were first made in 1837 by fusing aluminum oxide with chromium oxide. They are used in watches, scientific instruments, masers, and lasers.
Synonyms and Related Terms
red corundum; aluminum oxide; pigeon blood; rubin (Dan., Pol., Sven.); Rubin (Deut.); rubis (Fr.); robijn (Ned.); rubi (Esp.,Port.)
Trigonal crystal system. Strongly pleochroic. Fracture= uneven or conchoidal.
Streak = white. Luster = vitreous.
With high temperatures, ruby becomes green but returns to red on cooling. Fluoresces and phosphoresces a vivid red.
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