Jewelry is measured by grams, carats and pearls. Zhuke is a commonly used unit of measurement for pearls. 1 juke is equal to 1/4 carats, which is 0. 25 carats. _ Diamond Pictures First of all, we need to know what "carat" is. Cara is also called Kara, and sometimes it is simply called Ka. English carat is often abbreviated as ct. It is the mass unit of colored gems and diamonds, and also the purity ratio of precious metals. 1907 has been used since it was internationally recognized as a gem measurement unit. 1 carat equals 0. 2 grams or 200 milligrams. For relatively small gemstones below 1 carat, it will be represented by a point, 1 carat.