Importance of Diamond Cut

The Cut of a diamond is arguably the most important of the 4Cs, as it has the biggest impact on a diamond’s beauty and sparkle. This aspect is very complex, but incredibly crucial to the diamond’s value and appearance. When cut to exacting proportions, a diamond will sparkle and return light unlike anything else. How a diamond is cut has a direct impact on the three main effects of its appearance:


Brightness created from a combination of reflected white lights


Flashes of spectacular color seen through all aspects of the diamond


Areas of light and dark that reflect when the diamond is moved

Diamond Cut Chart 4Cs

Grading the Cut of a Diamond

A diamond’s cut grade is the only factor that is influenced by a human hand. A master cutter will apprentice for at least 10 years before touching a 1 carat diamond. These highly-skilled craftsmen bring the ultimate beauty of the diamond to life by adhering to specific parameters in order to maximize sparkle. Several individual factors are evaluated to determine the cut grade of a diamond including its proportions, depth, symmetry, polish and finish.

The GIA uses the following scale to grade round brilliant diamonds:


An excellent cut diamond has a maximum amount of scintillation, brilliance and fire. Light enters the diamond and refracts back out with very little light lost. This exceptional grade represents roughly the top three-percent of diamonds.


A diamond with a very good cut grade will reflect most of the light and will appear somewhat similar to an ideal cut diamond. This diamond will have superior sparkle, brilliance and fire.


Reflecting most of the light entering the diamond, this diamond cut has above average beauty. Diamonds with this grade won’t have as much brilliance and fire as higher cuts.


Diamonds graded Fair don’t have the optimum brilliance and fire, as they allow a significant amount of the entering light to exit on the bottom or side of the diamond instead of through the top. These are still quality, but not nearly as well performing as a finer cut.


Diamonds with a poor cut may appear dull because the majority of the light is lost through the bottom or sides of the diamond. With a noticeable decrease in sparkle, even an untrained eye can see a sharp difference between this and higher cuts.

The American Gem Society grades diamonds based on a ten-point scale, which can be seen below.

Diamond Cut Quality Scale by AGS

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