Diamond carat weight

The carat is the unit of weight for a diamond.
The size of a diamond can increase its value and rarity, but is less important if it is not matched with a good grade of color and clarity, and cut with proper proportions. Two stones with the same carat weight may have a very different value depending on the other characteristics.

Nevertheless, size does indeed contribute to increase the value of a diamond, as large stones are rarer than small ones. ​

Image representing diamond clarity.
Diamond clarity