Spinel is magnesium aluminum oxide, and in its pure state, it is colorless. Chemical impurities give rise to a range of colors, most typically pink or red, purple, green, and blue. The 22.20-carat rosy pink spinel from Sri Lanka and the 36.10-carat red spinel from Burma owe their color to impurities of chromium. Natural spinel crystals, octahedral in shape, are also pictured in the photograph.
Catalog Number: G2166, G3685
Weight: 22.20, 36.10 carats
G2166: Chamberlain Fund, 1937; G3685: Exchange, 1961