Cut is probably the most important, and most challenging, of the four Cs to understand. The brilliance of a diamond
depends heavily on its cut.
Apart from the general shape of the diamond, "cut" refers to the reflective qualities of the diamond. A good cut gives
a diamond its brilliance, i.e. the brightness that seems to come from the very heart of a diamond.
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 results in brilliance, 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, causing the stone to appear dark. Less light
reflected back to the eye means less brilliance.
Certain proportions have been found to radiate the maximum amount of brilliance. The most important factors are
how the depth compares to the diameter, and how the diameter of the table compares to the diameter of the
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: Ideal, Premium, Very Good, Good, Fair & Poor
Selecting the grade of cut is really a matter of preference. To make the best selection, you need to understand the
various grades. Please note that the descriptions below are general guidelines.
This cut is intended to maximize brilliance. Ideal cut diamonds generally have smaller tables, complemented by a
great deal of light dispersion, or fire. GIA's Excellent-Excellent stones, as well as AGS 000 stones fall into this
category. This category applies only to round diamonds.
Also intended to provide maximum brilliance and fire, premium cut diamonds can be generally found at slightly lower
price points than Ideal cut diamonds.
These diamonds reflect most of the light that enters, 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.
Diamonds that reflect much of the light that enters them. Such stones result from the cutter's choice to create the
largest possible diamond from the original rough crystal, rather than cutting extra weight off to create a smaller
Premium 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. Often these stones are
bought and re-cut into Ideal or Premium cuts, such that a more brilliant stones is produce by sacrificing some weight.
4Cs DIAMONDS GUIDE
Ideal Cut Fine Cut Shallow Cut Deep Cut