The diamond cut is a very important aspect of the four Cs, so it is important to understand how this quality affects the properties and values of a diamond. A good cut gives a diamond its brilliance, which is that brightness that seems to come from the very heart of a diamond. The angles and finish of any diamond is what determines its ability to handle light, which leads to brilliance.
As shown in the images below, 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 we mentioned, and it’s this flashing, fiery effect that makes diamonds so mesmerizing.
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.
TIP: Variance in the proportions between an Ideal Cut and a Poor Cut can be very difficult to discern by the casual untrained observer.
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:
This cut is intended to maximize brilliance, and the typically smaller table sizes of these diamonds have the added benefit of creating a great deal of dispersion or ‘fire’ as well. Ideal quality diamonds are truly for the person who enjoys knowing that he has one of the finest things that money can buy. This category applies only to round diamonds.
These diamonds reflect most of the light that enters them, creating a good deal of brilliance. With these diamonds, the cutters have chosen to stray slightly from the preferred diamond proportions in order to create a larger diamond. The result is that these diamonds fall slightly outside of some customers’ preferences in terms of, for example, table size or girdle width, though, in many cases many of the parameters of diamonds in this range will overlap with certain parameters of diamonds in the Ideal range.
Diamonds that reflect much of the light that enters them. Their proportions fall outside of the preferred range because the cutter has chosen to create the largest possible diamond from the original rough crystal, rather than cutting extra weight off to create a smaller higher quality diamond. Diamonds in this range offer an excellent cost-savings to customers who want to stay in a budget without sacrificing quality or beauty.
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.