The cut in a diamond has three components, Polish, Symmetry and proportions. Proportions are the measurements and angle at which the various facets are made in a diamond. Today all the proportions are calculated using sophisticated instruments, A lot of scientific research has gone into the proportions that are used in todays diamond manufacturing process. When a diamond is cut with poor or good proportions, the light that enters the diamond does not gets reflected multiple times before it reaches you. This results in a diamond that can not take the maximum advantage of the optical property of a diamond and thus the diamond does is not able to show the best possible brilliance, fire and scintillation. Any compromise on the proportions will result in a diamond that lacks in beauty. Only diamonds cut with Excellent to Very Good proportions results in diamonds with the best brilliance fire and scintillation and thus are the most beautiful diamonds.