The most important of the 4Cs—cut—refers to how a diamond’s facets interact with light. It is determined by symmetry, proportion and polish. More than any other factor, cut determines the beauty of the stone. If a diamond is cut poorly, it will appear dull even if it has a high color and clarity grade. If a diamond is cut well, it will reflect and refract light for maximum brightness and sparkle. Cut is the only one of the 4Cs that is affected by human hands. Two diamonds may have the same clarity, color and carat weight, but cut is what determines whether or not one is superior to the other. Put simply, cut is responsible for the quality and degree of a diamond’s sparkle.