Carat weight means the weight of the diamond. In the twentieth century diamonds were measured by carob seeds, which were very small and fit as a counter weight for the diamonds. So the term “Carat” is derived from carob. Simply, the carat is a unit of mass equal to 200mg, and is used for measuring gemstones, diamonds and pearls. The size of a diamond is proportional to its carat weight, when a rough diamond cut and polished to convert into furnish diamond, it’s ⅔ of the total carat weight. When looking for the diamond engagement rings, it is difficult to measure the diamond carat weight. Although carat weight affect the cost of a diamond quite a bit.