Carat (mass)

The metric carat is a measure of the mass of precious stones. 1 metric carat = 0.2 g = 2 · 10-4 kg.

The metric carat is not an SI unit, but in the countries of EU and Switzerland is a legal entity. It is also described in DIN 1301-1. The carat has no legal unit characters; common in Germany, the character " Kt ", in Switzerland and in Austria is "ct " set as unit characters.


The carat is a loanword from the French le carat from the medieval Latin carratus. This originated on the Arabian قيراط / Qirat from the Greek κεράτιον keration ( diminutive of κέρας keras " horn " ), as the fruit ( pod ) of the carob tree is croissant -shaped. The seeds of these fruits were formerly often used as weight stones. Allegedly (0.2 g and weight of the resulting uniform on average), this was done because of their uniform size. However, modern research refutes this uniformity.


Originally, the carat, the weight of a dried seed kernel of the carob tree ( Ceratonia siliqua ). In medieval times one carat equal to the weight of three barley or four grains of wheat.

The metric carat was introduced in 1875, the Metre Convention. 1 metric carat = 200 mg = 0.2 g; which corresponds to about 4 depending on the definition Gran