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very hard mineral used as an abrasive
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any of various forms of aluminum oxide occurring naturally as corundum
a transparent deep red variety of corundum; used as a gemstone and in lasers
a precious transparent stone of rich blue corundum valued as a gemstone
a substance made of fused alumina
a sapphire that when cut shows a starlike figure in reflected light because of its crystalline structure
solid homogeneous inorganic substances occurring in nature having a definite chemical composition
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