名词（宝石的重量单位）克拉; ，（金子）开（以纯金为24开表示金含量的单位）; =karat

1. 克拉(钻石等宝石的重量单位,合0.2克)
A carat is a unit for measuring the weight of diamonds and other precious stones. It is equal to 0.2 grams.

e.g. The gemstone is 28.6 millimetres high and weighs 139.43 carats.
这块宝石高28.6毫米,重139.43克拉。
e.g. ...a huge eight-carat diamond.
重达8克拉的大钻石

2. 开(表示黄金的纯度,纯金为24开)
Carat is used after a number to indicate how pure gold is. The purest gold is 24-carat gold.

e.g. ...a 14-carat gold fountain pen.
14开金钢笔

noun

1. the unit of measurement for the proportion of gold in an alloy
18-karat gold is 75% gold
24-karat gold is pure gold

Synonym: karatkt

2. a unit of weight for precious stones = 200 mg