A diamond’s cut is the only factor that is controlled by human hands. An expert diamond cutter, known as a lapidary, brings out the brilliant qualities of diamond rough. A diamond’s cut refers to the way light is reflected from one facet to another and then dispersed through the stone and back to the eye. This refraction of light gives diamonds their unique brilliance. For this reason, premium and ideal cut diamonds may demand a premium.

Diamonds are cut into a variety of shapes. The most popular shape is the round brilliant, but trends in fashion have increased demand for fancy cut stones. Although no one shape has more value than the others, the market fluctuates occasionally, due to trends and other factors increasing demand for particular shapes and thereby commanding a premium. Some of the more common diamond shapes are detailed below.

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	Round Brilliant The most popular of all cuts the brilliant cut. It is comprised of 58 facets. In its Ideal proportions, it is designed to give maximum scintillation, beauty and fire. Unlike white round brilliant diamonds, exact proportions are not as critical with colored stones.
	Princess Cut The princess is one of the most popular fancy diamond shapes. The proportions are considered to be “ideal” the squarer the stone is cut, with exact 90 degree internal angles on each corner. Princess cut diamonds can also be slightly rectangular in shape. On a certificate, this cut will be referred to as a Square Modified Brilliant.
	Oval The oval cut is also a particularly beautiful shape and if well proportioned - gives great brilliance and fire. A well cut oval diamond can be almost as bright as an ideal cut round, as the angles for cutting are similar to that of a brilliant cut diamond.
	Heart The heart shape diamond is preferred mostly based on an emotional level. The shape is a traditional symbol of love and adoration. The technical benefit of a heart shape is that it has a slightly round pavilion and if it is well cut and proportioned it can adequately reflect the sparkle and scintillation back out of the diamond. This particular shape is popular in earrings and pendants.
	Marquise The Marquise is a slender cut similar to the shape of a football. The shape is visually bigger because of bigger table spread for carat weight than traditional cuts.
	Emerald The emerald cut uses a series of flat rectangular facets stepping down off the table to give it a unique brilliance, quite different to that of a round or curved shaped cut.
	Trillion One of the more unusual shapes, the trillion, cut like a triangle, displays a very sharp brilliance or fire if the diamond is cut to the correct depth.
	Pear The pear cut uses the base of a brilliant or round cut and extends to a fine point. A well proportioned cut will give a depth of scintillation to the point of the stone. If a longer look is desired from a design perspective, the pear shape will provide this characteristic nicely, without sacrificing brilliance.
	Radiant The radiant can either be cut as a square or rectangle. The radiant has a strong look with a unique type of sparkle, differing from emerald and princess cuts. A GIA will refer to this tone as a cut-cornered modified brilliant.
	Cushion The cushion cut diamond is one of the most popular cuts of all time. For more than 70 years, from 1830 to 1900, this was how almost all diamonds were cut. Sometimes referred to as a "pillow cut", the cushion cut has an open culet (the bottom of the diamond) and a rectangular to square shape with rounded corners. GIA will refer to this stone as a cushion cut modified brilliant.