A 3 carat diamond weighs roughly 3 carats, which is equal to 600 milligrams or 6/10ths of a gram. The size of a 3 carat diamond is affected by a number of elements, including the diamond's shape and cut, as well as its clarity and color. A 3 carat diamond is massive, with a diameter ranging from 9.5 to 11.4 mm. The quality of a 3 carat diamond determines its worth, with higher quality diamonds (for example, superior cut, clarity, and color grade) being more valuable than lower quality diamonds.