How big is a ctw?

A carat weight (ctw) is a unit of measurement used to express the weight of gemstones and pearls, where one carat is equivalent to 200 milligrams or 0.2 grams. Carat weight does not directly indicate the size or volume of a gemstone, as factors like cut and shape also play significant roles in how large a stone appears. For example, two stones with the same carat weight can look different in size depending on their cut.