The cut of a diamond refers to its proportions or its ability to reflect light. Of the 4C’s, the cut is the aspect most directly influenced by man. The other three are dictated by nature. Quite often the cut of a diamond is confused with its shape. Diamonds are cut into various shapes, depending upon the original form of the rough. Whatever the shape, a well-cut diamond is better able to reflect light. A diamond’s ability to reflect light determines its display of fire and brilliance. Diamonds are usually cut with 58 facets. These facets follow a mathematical formula and are placed at precise angles in relation to each other. This relationship is designed to maximize the amount of light reflected through the diamond and to increase its beauty.
Ideal – When a diamond is cut to proper proportions, light is reflected from one facet to another and then dispersed through the top of the stone.
Deep – When the cut of a diamond s too deep, some light escapes through the opposite side of the pavilion.
Shallow – When the cut of a diamond is too shallow, light escapes through the pavilion before it can be reflected.
The cut, or proportions, of a diamond is measured in percentages relative to the diameter of it’s girdle. The girdle diameter of each diamond is always considered 100%. The table and depth percentages are the key to determining good proportions.
The 4 C's of Diamond Value
Watch the Video (3min)Gemological Institute of America