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Diamond cut is perhaps the most important of the four Cs, so it is important to understand how this 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 are what determine its ability to handle light, which leads to brilliance. The way a diamond is cut, its width, depth, circumference, size, and position of the facets determine that brilliance factor. Even if the color and clarity are perfect, if the diamond is not cut to good proportions, it will be dull and less impressive to the eye.

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 is the brilliance we mentioned, and it’s this flashing, fiery effect that makes diamonds so mesmerizing. In a poorly cut diamond, the light 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.

Most gemologists agree that the best cut diamonds are those that follow a set mathematically calculated formula to maximize brilliance. This formula is applied and used in grading the diamonds proportions, most importantly how the depth compares to the diameter of the diamond. Cut and proportioning can account for a 20 to 40 percent difference in price between diamonds that are otherwise equal.

Jeweler A may offer you a SI1/H 1.00ct diamond for $6,500.00.

Jeweler B may offer you a SI1/H 1.00ct diamond for $5,000.00.

You may think Jeweler B is giving you a significant discount directly from the wholesalers or the diamond mines, but what they don’t tell you is that you are getting a shallow or deep cut diamond and not an ideal cut. When you shop for diamonds there is more to diamond grading/pricing than just carat, clarity, and color. There is also the very important cut grade. 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, and Poor. Selecting the grade of cut is really a matter of preference. To make the best selection, you need to understand the various grades. Note that these descriptions are general guides.

Ideal Cut
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 to round diamonds.

Premium Cut
In the case of round diamonds, many Premium Cut diamonds have cuts that are the equal Cut diamond, though they often can be purchased at slightly lower prices than AGS Ideal Cuts. They are intended to provide maximum brilliance and fire. Like the Ideal Cut, these are also for the person who enjoys knowing that he has one of the finest things that money can buy.

Very Good
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 or Premium Cut ranges. Generally, the price of these diamonds is slightly below that of Premium Cuts.

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 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. Typically these diamonds have been cut to maximize the carat weight over most other considerations.