Plural of corundum; multiple samples or types of the hard mineral aluminum oxide.
From Sanskrit kuruvinda via Persian and Arabic into English, with the English plural suffix -s added. The word maintains its singular form from Sanskrit in modern English.
Industrial corundums are synthetic—we now make them in laboratories using electric furnaces, and these human-made gems are actually purer and more perfect than natural ones, which sometimes feel like cheating on nature.
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