Diamond Cut

Do not confuse diamond "cut" with diamond "shape." Shape refers to the general outward appearance of the diamond; Cut is the description of the proportion and symmetry of the cutting and polishing of a diamond.

Diamond cut is the most important of the four C’s, so it is important to understand how this quality affects the properties and values of a diamond. A better cut gives a diamond its brilliance, which is the flash of light, or fire, that comes from the centre of a diamond. The angles and finish of any diamond are what determine its ability to reflect light, which leads to brilliance.

When a diamond is well-cut, light enters through the table and travels to the pavilion where it reflects from one side to the other before reflecting back out of the diamond through the table and to the observer's eye. This light is the brilliance and it's this flashing, fiery effect gives diamonds life.
Diamond cut

In a poorly cut diamond, the light that enters through the table reaches the facets and then 'leaks' out from the sides or bottom of the diamond rather than reflecting back to the eye. Less light reflected back to the eye means less brilliance.

Correct Proportions are important
The best cut diamonds are those that follow a set of formula calculated to maximize brilliance.

However, the variance in the proportions between an Excellent cut and a Very good cut cannot be seen by an untrained eye. With a Fair or Poor cut, there will usually be a visible difference.

Because cut is so important, several grading methods have been developed to help consumers determine the cut of a particular diamond. In general, these grades are:

  • Excellent
  • Very Good
  • Good
  • Fair & Poor

Excellent Cut
This cut is intended to maximize all the different attributes of the diamond and to maximize its beauty. These diamonds are harder to process and are priced at a premium to other cuts.

Very Good
These diamonds reflect most of the light that enters them, creating a good deal of brilliance. Many of the parameters of diamonds in this range will overlap with certain parameters of diamonds in the Excellent cut, and the price may be slightly less than the Excellent cut.  Again it is worth noting that the variance in the proportions between an Excellent cut and a Very Good cut cannot be seen by an untrained eye.

Diamonds that reflect much of the light that enters them. Many proportions may fall outside of the preferred range because the cutter has chosen to maximize the yield of the rough diamond. These diamonds may be significantly cheaper than Excellent and Very Good cut diamonds.

Fair & Poor
A diamond graded as fair or poor reflects only a small proportion of the light that enters it. Typically these diamonds have been cut to maximize the carat weight over most other considerations.

Diamond Anatomy

Diamond Anatomy

  • Diameter
    The width of the diamond as measured through the girdle.
  • Table
    This is the large, flat top facet of a diamond.
  • Crown
    The upper portion of a cut gemstone, above the girdle.
  • Girdle
    The narrow rim of a diamond that separates the crown from the pavilion. It is the largest diameter to any part of the stone.
  • Pavilion
    The lower portion of the diamond, below the girdle. It is sometimes referred to as the base.
  • Culet
    The tiny facet on the pointed bottom of the pavilion, which is the portion of a cut gem below the girdle.
  • Depth
    The height of a gemstone, from the culet to the table.
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