The 4 C’s Of Diamond Grading

Diamond Grading

When you are planning to purchase a diamond it is extremely important that you understand the four different factors used to classify and appraise the value a diamond. The 4 C’s consist of Cut, Color, Clarity, and Carat (weight). Read below so that you will learn how and why each of these aspects are important alone and why each of them in combination together allow a certified gemologist to render a consistent opinion as to the value of a diamond.


The “cut” refers to the actual style used when shaping the diamond. It does not actually refer to the shape of the diamond but to the symmetry, proportions and polishing of the diamond. The type of cut significantly affects the brilliance of the diamond; if it is cut poorly, it will be less brilliant in how it reflects light. The most common cuts are:


A pure and structurally perfect diamond is transparent with no color. However, it is very rare to find a gem-sized diamond that is absolutely perfect. The color of a diamond can be affected by structural defects in the stone itself and/or by chemical impurities. Depending on the tint and concentration of a diamond’s coloration, the color can either enhance or detract from its value. Most white diamonds are less valuable when more yellow is visible while an intense blue or pink diamond can be dramatically more valuable.

Diamonds occur in many colors – black, white, blue, yellow, orange, steel gray, green, pink to purple, and red. Of all the colored diamonds, the rarest are red diamonds. Colored diamonds contain impurities or structural defects that cause the coloration; the more pure the diamond, the less color it has, as in white diamonds. The purest diamonds are colorless and transparent.

Most diamonds that are mined are in a range of pale yellow or brown that is called “normal color range.” Diamonds that are an intense yellow or brown, or any other color, are called “fancy color diamonds.” Diamonds that are of the very highest purity are totally colorless and appear bright white. The degree to which diamonds show color is one of the four factors used to assess the diamond’s value.


Diamond clarity is an evaluation that relates to the existence and visual appearance of internal stone characteristics called “inclusions” and surface defects called “blemishes.” Inclusions can be crystals of a foreign material or another diamond crystal, or structural imperfections such as cracks that may appear cloudy or white. A clarity grade is based on the overall appearance of the stone under 10 times magnification. The number, size, color, location, orientation and visibility of inclusions all affect the relative clarity of a diamond.

Diamonds with a high clarity grade are more valuable, and the extremely rare “flawless” graded diamond will capture the highest price. Sometimes minor inclusions and blemishes can be useful because they help to identify a diamond, much like a fingerprint. And, as synthetic diamond technology improves and it becomes more difficult to distinguish between natural and man-made diamonds, inclusions and blemishes can be used as a proof of natural origin.

Most of the inclusions in gem-quality diamonds do not affect their structural integrity and are not visible to the naked eye. But, large cracks close to the surface may reduce the diamond’s resistance to fracture and large clouds internally will affect the diamond’s ability to reflect and scatter light.


The carat (ct) is a unit of mass equal to 200 mg and is used for measuring diamonds. The current definition, sometimes referred to as the “metric carat” was adopted in 1907 at the Fourth General Conference on Weights and Measures and was soon afterwards adopted in many countries around the world. The carat is divisible into 100 points of two milligrams each. You will often see diamonds referred to as number of carats or fraction of a carat. But you may also hear smaller diamonds referred to as a point size. So, for example, a 25 point diamond is the same as a 1/4 carat diamond.

You have to be careful when evaluating the size of a diamond, because it is a measure of weight and the cut of the diamond affects the look of how big a diamond is. For example, you could find a poorly cut 2 carat diamond that looks bigger than a well cut 2 carat diamond but the first one is “fat” on the top and will reflect light poorly while the well cut diamond may be smaller on the crown but deeper and will give off the light and brilliance that makes it a far superior diamond. Only a certified gemologist is trained and qualified to accurately measure the size of a diamond.


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 We recommend appointments for custom design and appraisals. 

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Telephone: 520-795-5496
Address: 2464 N. Campbell Avenue (Parking is available behind the building)

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Viir Fine Jewelry & Art

2464 North Campbell Ave.

2464 N. Campbell Avenue
(Parking available behind building)