carat
/ˈkærət/noun
1
- a unit of weight for precious stones and pearls, now equivalent to 200 milligrams克拉（宝石、珍珠重量单位, 现等于200毫克）：
a half-carat diamond ring.
一枚半克拉的钻石戒指。
2
- （〈美〉亦作karat）a measure of the purity of gold, pure gold being 24 carats开（金纯度单位, 纯金为24开）：
an ounce of 23-carat gold.
一盎司23开金。
词源
late Middle English (in sense 2)： from French, from Italian carato, from Arabic ḳīrt (a unit of weight), from Greek keration 'fruit of the carob' (also denoting a unit of weight), diminutive of keras 'horn', with reference to the elongated seed pod of the carob.