Diamond ct refers to the quality unit of diamonds and other precious stones, transliterated as carat, which has been used since 1907 was internationally agreed as the quality unit of diamonds and jewels. Girls' favorite one-carat diamond ring, inlaid with 1ct diamonds. According to international regulations, the weight of 1ct diamond is 0.2g, which is equivalent to 200mg. Fine diamonds below 1ct can also be expressed in carats (ct), with diamonds of 1 carat being 100 and diamonds of 0.5 carat being 50. As a mass unit, ct is often used to represent the weight of diamonds and jewels. Diamonds of the same quality, the greater the weight, that is, the greater the ct, the more expensive the price will be. When the weight of diamonds reaches 0. 1 carat, 0.2 carat and 0.3 carat, the price will go up a step, and the price is directly proportional to the geometric progression of weight.