about weight, not size
What is Diamond Carat?
Carat denotes the weight of a diamond, not the size. One carat equals 0.2 grams. Royal Asscher diamonds are cut to maximum beauty, not carat weight.
Carat weight can appear differently across different diamond shapes. A diamond may have a higher carat weight without appearing larger and two diamonds of the same carat weight can vary in size if one is cut deeper than the other. While everyone loves the glamour of a large carat diamond, two diamonds of the same weight can vary widely in price when clarity, color, and cut are considered.