DIAMOND CUT is the king of 4Cs. Diamond cut is all about, how the diamond is cut in terms of proportions, symmetry and polish. Diamond cut determines how the diamond will perform. The brilliance, fire and scintillation which you see in your diamond ring is all related to the way the diamond is cut. Cut of the diamond may increase or decrease its overall value.
A diamond should not be cut too deep or too shallow. A diamond should be cut with ideal proportions to achieve the maximum reflection of light. An excellent cut diamond will have a lot of brilliance, fire and scintillation; however a poor cut diamond will lack brilliance.