What are the 4Cs of a diamond, especially when it comes to diamond grading?

DIAMOND CUT

Of all the 4Cs, Cut has the greatest effect on a diamond’s beauty. In determining the quality of the cut, the diamond grader evaluates the cutter’s skill in the fashioning of the diamond. The more precise the cut, the more captivating the diamond is to the eye.

A Diamond’s Cut Unleashes Its Light

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Diamonds are renowned for their ability to transmit light and sparkle so intensely. We often think of a diamond’s cut as shape (round, heart, oval, marquise, pear), but a diamond’s cut grade is really about how well a diamond’s facets interact with light.

Precise artistry and workmanship are required to fashion a stone so its proportions, symmetry and polish deliver the magnificent return of light only possible in a diamond.

DIAMOND COLOR

Diamond Color Actually Means Lack of Color

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The diamond color evaluation of most gem-quality diamonds is based on the absence of color. A chemically pure and structurally perfect diamond has no hue, like a drop of pure water, and consequently, a higher value. GIA’s D-to-Z diamond color-grading system measures the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to masterstones of established color value.

Many of these diamond color distinctions are so subtle that they are invisible to the untrained eye; however, these distinctions make a very big difference in diamond quality and price.

This short video explains the GIA color scale and how GIA classifies a diamond with a letter grade from D-to-Z by comparing it to master stones representing the color grades on the GIA scale.

DIAMOND CLARITY

Diamonds can have internal characteristics known as inclusions or external characteristics known as blemishes. Diamonds without inclusions or blemishes are rare; however, most characteristics can only be seen with magnification.

DIAMOND GRADING

Since many inclusions and blemishes are very small, and can be difficult to see with the naked eye, they are graded at 10x magnification. Grading at 10x is an industry standard to determine the final clarity grade of the diamond.

Diamond graders plot the inclusions they see in the diamond on a diagram which is included on diamond grading reports.

Clarity grade is determined on a scale of decreasing clarity from the highest clarity (Flawless or FL) to the lowest clarity (Included 3, or I3).

THE CLARITY SCALE

The clarity scale originated because jewelers were using terms that were unstandardized and could be easily misinterpreted. Descriptive terms such as “eye clean,” or “included” were vague and didn’t communicate the clarity of the diamond effectively.

The modern clarity scale was invented in the 1950s, by a former president of GIA, Richard T. Liddicoat, Jr. With minor modifications, it has been the universal standard ever since, using verbal descriptors most are now familiar with: Flawless, Internally Flawless, VVS1, VVS2, VS1, VS2, SI1, SI2, I1, I2, and I3.

DIAMOND CARAT

The carat is the diamond’s physical weight measured in metric carats. One carat equals 1/5 gram and is subdivided into 100 points. Carat weight is the most objective grade of the 4Cs.

How Carat Weight Plays Into the 4 Cs and Diamond Value

Carat weight is the most objective of the diamond’s 4Cs. All that is required is a precisely balanced scale capable of measuring extremely small weights. In the AGS Laboratories, carat weight is measured using a highly accurate, and calibrated digital scale.

Here are some facts about a diamond’s weight and price that are important to understand before purchasing.

Comparing the value of diamonds by carat weight is like comparing the value of paintings by size. A wall-sized canvas by an unskilled artist may be bigger than a miniature by Rembrandt, but it will not be worth more. Large diamonds are rarer than smaller ones, and as the carat weight increases, the value of the diamond increases as well. However, the increase in value is not proportionate to the size increase.