[ 'karət ]
■ noun
1》 a unit of weight for precious stones and pearls, equivalent to 200 milligrams.
2》 ( US also karat ) a measure of the purity of gold, pure gold being 24 ~s.
Origin
ME: from Fr., from Ital. ~o , from Arab. ḳīrāṭ , from Gk keration 'fruit of the carob'.