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Diamond Cut Grade Guide – Chart, Pictures and Video

Cut is the one of basic criterion a person starts choosing and assessing diamonds with. Both the beauty and the price of the gem depend on it. High-quality cut provides a diamond with a unique glare, which seems to come from the very heart of the gem. Let’s look closer at how the glow appears using the example of a round diamond. The amount of light reflected in the faces of the diamond directly depends on the proportions, defined by the cut of the gem.
The third C is cut. The GIA cut scale is used for round brilliant-cut diamonds and consists of five grades ranging from excellent to poor. You may think of cut is the shape of a diamond like square cut or round, however there is much more to cut than the basic shape. How a diamond is cut and polished directly affects the amount of sparkle and brilliance that comes off the stone, when it interacts with light:

  • How light strikes the surface
  • How much enters the diamond
  • How and in what form light returns to your eye

A polished diamonds proportions affect its light performance which in turn affects its beauty and overall appeal. Ideal Cut DiamondDeep Cutshallow cut diamond


GIA diamond is placed in a highly precise measuring device that rotates the stone 360 degrees to optically capture hundreds of measurements and fasten angles enough to generate a 3d model of the actual diamond. Since there is no single set of proportions that define a well cut diamond. A cut grade needs to be determined by factoring in a range of parameters. After 15 years of research GIA science has developed a comprehensive system that factors the Diamonds proportions as well as its culet sighs, girdle thickness, polish and symmetry descriptions and generates a GIA a cut grade. Learn about the most complex of the 4Cs, diamond cut, with this video