4 Carat Diamonds are said to be 800 milligrams or 4/5 grams. The dimensions of a 4 carat diamond depend on its size, cut, and clarity. Usually, the diameter of a 4-carat diamond is between 10.1mm to 12.5mm. Celebrate love in bold fashion with a 4 carat diamond from ShivShambu. Visit our online store to buy 4 carat diamonds.