A diamond in its natural, uncut state is described as a "rough diamond". Its natural appearance so resembles a glass pebble that most people would pass it by without a second glance. It is the skill of the diamond cutter that unlocks the brilliance for which diamonds are renowned. If two identical diamonds are placed side by side and one is less brilliant and fiery than the other, the fault lies in the cutting.
Such a stone cannot demand as high a price as a well-cut diamond. It is important to distinguish between cut and shape. Some of the more popular shapes of diamonds include Round Brilliant, Oval, Marquise, Pear, Heart and Emerald. Within each of these shapes, however, it is the cut that determines the quality of the stone.