carat

1. N-COUNT Carat is used after a number to indicate how pure gold is. The purest gold is 24-carat gold. 开; 黄金纯度

...a twenty-four-carat gold necklace. ...一条二十四开金的项链。

2. N-COUNT A carat is a unit for measuring the weight of diamonds and other precious stones. It is equal to 0.2 grams. 克拉 (钻石等宝石的计重单位，相当于0.2克)

The gemstone is 28.6 millimetres high and weighs 139.43 carats. 这颗宝石高28.6毫米，重达139.43克拉。