a unit of weight for precious stones = 200 mg
"The jeweler weighed the diamond on a precise scale to ensure it was exactly two carats."
A unit of weight for precious stones and pearls, equivalent to 200 milligrams.
"The diamond's brilliant sparkle was due to its perfect cut and high carat weight."
In plain English: Carat is a unit of weight used to measure how heavy diamonds and other gemstones are.
"The diamond in her engagement ring is two carats and sparkles beautifully."
Usage: Carat measures the weight of gemstones rather than their purity or quality. Do not confuse it with carats per thousand, which is a different measurement used specifically for gold alloys.
From Middle French carat, from Italian carato, from Arabic قِيرَاط (qīrāṭ, "carat, similarly small units such as inches"), from Ancient Greek κεράτιον (kerátion, "hornlet, carob seed"), from κέρας (kéras, "horn") + -ιον (-ion, diminutive suffix). Doublet of quilate and keratin.