A carat is a unit of weight used to measure gemstones and pearls. One carat is equivalent to 200 milligrams, or 0.2 grams. The term is derived from the carob seeds that were historically used as a balance scale to weigh precious stones. Carat weight is an important factor in determining the value of a gemstone, with larger stones generally being more valuable. In addition to weight, the quality of a gemstone is also assessed using the Four Cs: carat, cut, color, and clarity. Each of these factors contributes to the overall appearance and desirability of the stone. Understanding carat weight helps buyers make informed decisions when purchasing jewelry.