Of all the 4 C's, the Cut is the most directly influenced by man. The other three are dictated by nature. Not to be confused with the shape of a diamond, Cut refers to the arrangement of a diamond's facets. A brilliant diamond that is correctly cut captures and releases the maximum play of light.
To achieve this, the diamond cutter must adhere to a whole series of exacting tolerances. These tolerances, in turn, may well mean that much of the rough diamond has to be cut away. Very few diamonds are cut to "Very Good" or "Excellent" symmetry proportions. A diamond with a GIA Diamond Grading Report with these ratings is the exception rather than the rule.
Many people confuse cut with the shape of a diamond. Shape, which is not to be confused with Cut, merely means the geometric form of the diamond. In its natural state, a diamond's beauty is generally concealed. What draws out its brilliance is the cutting of the diamond. Under ideal circumstances cutting maximizes the optical properties within the diamond, particularly its ability to refract light and disperse color. The shape is largely a matter of personal preference and is only limited by the skill and imagination of the craftsman. The eight most popular shapes for diamonds are the ROUND BRILLIANT, PEAR, OVAL, MARQUISE, PRINCESS, HEART, EMERALD, and RADIANT CUT.