BRILLIANT - The basic brilliant cut stone is round or oval with many facets of different shapes and sizes. The cut increases the brilliance of the stone by minimizing the amount of light that escapes at the bottom of the stone.
CABOCHON - A stone with the upper side polished to a smooth, rounded domed surface with no facets. The back of the stone is flat and unpolished, originally so that the stone's structure and size was recognizable. Usually it is cut from an opaque or translucent stone. Stones with special optical effects are also cut "en cabochon" (e.g. opal or tiger's eye). Usually a cabochon is round or oval.
CUSHION - A stone cut with a square or rectangular shape, but having rounded corners.
EMERALD - The style of cutting a large transparent gemstone in a square or rectangular shape with diagonal cut corners. The sides are step cut-there are sloping parallel facets that increase in size as they approach the widest part of the stone and decrease as they reach the bottom.
FANCY - An unusual shape, not able to be categorized under any other description!
HEART-SHAPED - Faceted like a brilliant cut stone, but in the form of a heart.
MARQUISE - A modification of brilliant.
PEAR-SHAPED - Shaped like a drop of water-pointed at one end and round at the other.
RADIANT - A rectangular stone that is flat on top and brilliant cut underneath.
ROUND - See brilliant cut.
SQUARE - The top is square with one step-cut facet on each side. A.k.a. Princess cut, quadrillion.
TRILLION - A triangle cut that is flat on top and brilliant cut underneath.