Diamond cut grades are determined based on the quality of proportions and finish of a polished diamond.

Diamond Cut Grades

Image credit: GIA

Cut has two meanings in the diamond and jewellery industry:

  1. The shape and style of a polished diamond, such as Round Brilliant or Emerald cut. See our diamond shapes page for more information.
  2. The "4Cs" meaning of cut, discussed below, describes the relative quality of the proportions and finish of a polished diamond.

In the diamond industry, cut is also commonly referred to as 'Make'. Finish is another term used, which refers to the quality of a diamond's polish, the condition of its girdle, and the precision of the faceting.

Note that only round diamonds have cut grades on diamond grading reports (diamonds of other shapes do not).

The cut, or make, of a diamond is the most important of the 4Cs and is a complex area of study that is ongoing in the major diamond grading laboratories. Make is the only one of the 4Cs that man, the diamond cutter, can control.

Polished diamonds should be considered optical instruments and, ideally, all light entering a diamond should be internally reflected back to the observer (see the diagrams below).

The diamond cutter analyses a rough diamond to determine how to extract the most beauty from it. In a commercial environment, they also cut a diamond to retain the most weight possible and, therefore, increase its perceived value, to the uninitiated. However, this retained weight can be detrimental to a diamond's face-up appearance and such diamonds will appear as either very lumpy (small diameter) or very spread (wide diameter). This ties in with the minimum diameters that are recommended when purchasing round brilliant diamonds. See carat weight.

Diamonds with cut grades of "Fair" or "Poor" can have overly deep pavilions creating light leakage in the pavilion or overly shallow/spread pavilions creating the "fish eye" appearance. As a result, does not list diamonds with "Fair" or "Poor" make:

pavilion depth excellent
excellent cut
excellent cut profile

Excellent to Good Cut Grades:  Diamonds cut with Excellent, Very Good, and Good proportions allow a maximum amount of light to be returned to the observer and thus have more brilliance and fire

pavilion depth nail
cut nail
cut nail profile

Fair or Poor Cut Grades (light leakage due to deep pavilion): A diamond with an overly deep pavilion will appear dark in the centre due to the leakage of light from the pavilion*

pavilion depth shallow
cut shallow
cut shallow profile

Fair or Poor Cut Grades (fish eye due to shallow pavilion):  A spread "fish eye" diamond with an overly shallow pavilion creates a white circle at the edge of the table when looking down on the diamond, which is actually the reflection of the girdle at the edge of the table*

Next 4C: Colour