The 4C's of Diamond Quality

What does the numbers and letters such as D VVS1 and G SI2 mean? And where do they come from when talking about diamonds? Who decided this terminology and when did it become so universal across the entire industry?


Color, clarity, and carat were the basis for the first diamond grading system established in India over 2000 years ago. Gemological Institute of America, GIA, added the cut grade creating a globally accepted and understood standard for grading and for the quality of diamonds. The 4C’s are value factors that stand for: Color, Cut, Clarity, Carat (weight).

By creating this universal standard, GIA has helped improve the uniformity of the diamond industry in many different aspects. From the suppliers and distributors to us to you the customers, GIA has provided all of us the ability to speak a uniform language amongst ourselves that we can all understand.


Its our responsibility as jewelers and diamond retailers to provide you with as much knowledge as we possibly can in order to ensure that you make a well-informed and well-educated decision when buying jewelry. Regardless if you buy it through us or decide to make your purchase elsewhere, it's a standard we hold ourselves to.



A diamond’s color grade is actually based on the lack of color.


With diamonds, a higher given grade for color equates to less color the stone has. The grading scale ranges from D-to-Z. D being the highest, or colorless, and Z being the lowest on the range and showing distinct color.


Be careful to the fact that some diamonds that are lower on the color grading scale such as Z are unfortunately attempted to be passed off as a “fancy colored” yellow or “canary” diamond. As stated before, a diamond in the normal color range is graded upon how colorless the stone is. A true fancy colored diamond is considered outside of the normal color range, and its rarity is based upon how saturated its color is.


True fancy colored stones are very rare. Including red, green, and blue diamonds with medium to dark tones and even just moderate saturations, these are extremely rare. The grading process for these is extremely complex and specialized and must only be completed by highly trained laboratory graders.

Diamond color scale d-z Boise Nampa Meridian Garden City Eagle Star Kuna Caldwell Middleton Idaho

            S                     T                     U                V                  W                  X                   Y                     Z                       

                  J                   K                    L                 M                  N                 O                    P                  Q                       R              

                     D                            E                            F                           G                            H                                   I                           



A diamond's cut can make or break the brilliance.

Diamonds are well known for their ability to transmit light and sparkle intensely. Their brilliance is what sets them apart for all other gemstones and make us all adore them as much as we do. Often when we think of a diamond's cut, we think of its shape (round, princess, cushion), but a diamond's cut grade really is telling about how the diamond’s facets interact with light. It takes precision skill in order to establish its proportions, symmetry, and polish to ensure the magnificent return of light that is only possible in a diamond.


The diamond’s cut is a critical component in its final beauty and therefore its value as well. Out of the 4C’s discussed on this page, the cut is by far the most difficult to make an accurate technical analysis.

The following attributes allow GIA and other grading laboratories to evaluate how successfully a diamond interacts with light to create the pristine beauty diamonds are known for.

Brightness: Internal and external white light reflected from a diamond
Scintillation: The amount of sparkle a diamond produces and the pattern of light and dark areas caused by reflections within the diamond.
Fire: The scattering of white light into all the colors of the rainbow


The grading laboratory’s diamond cut grade also takes into account the design and craftsmanship of the diamond, including its weight relative to its diameter. Also it's girdle thickness (which affects its durability), the symmetry of its facet arrangement, and the quality of polish on those facets.

The GIA diamond cut scale for standard round brilliant diamonds in the D-to-Z diamond color range contains 5 grades. The ranges consist in order of excellent, very good, good, fair, poor.

Diamond clarity Boise Nampa Meridian Garden City Eagle Star Kuna Caldwell Middleton Idaho


The lack of inclusions and blemishes.

Natural diamonds are the result of carbon exposed to tremendous heat and pressure deep in the earth. This process can result in a variety of internal characteristics called 'inclusions' and external characteristics called 'blemishes.' Evaluating diamond clarity involves determining the number, size, relief, nature and position of these characteristics, as well as how these affect the overall appearance of the stone, While no diamond is perfectly pure, the closer it comes, the higher its value. Inclusions usually impact value more than blemishes due to blemishes being relatively easier to remove.









The GIA Diamond Clarity Scale has 6 categories, some of which are divided, for a total of 11 specific grades.

Flawless (FL): No inclusions and no blemishes visible under 10x magnification
Internally Flawless (IF): No inclusions visible under 10x magnification
Very, Very Slightly Included (VVS1 and VVS2): Inclusions so slight they are difficult for a skilled grader to see under 10x magnification
Very Slightly Included (VS1 and VS2): Inclusions are observed with effort under 10x magnification, but can be characterized as minor
Slightly Included (SI1 and SI2): Inclusions are noticeable under 10x magnification
Included (I1, I2, and I3): Inclusions are obvious under 10x magnification which may affect transparency and brilliance

Many inclusions and blemishes are too tiny to be seen by anyone other than a trained diamond grader. To a naked untrained eye, a VS1 and an SI2 diamond may look exactly the same, but these diamonds are quite different in terms of overall quality and value.



Diamond carat weight is the measurement of how much a diamond weighs.

A metric "carat" is defined as 200 milligrams. Each carat can be subdivided into 100 'points.' This allows very precise measurements to the hundredth decimal place. A jeweler may describe the weight of a diamond below one carat by its 'points' alone. For instance, the jeweler may refer to a diamond that weighs 0.25 carats as a 'twenty-five pointer.' Diamonds that weigh greater than one carat are expressed in carats and decimals. A 1.08 carat stone would be described as 'one carat oh eight.'











All else being equal, diamond price increases or decreases with diamond carat weight, because larger diamonds are rarer and more desirable. But two diamonds of equal carat weight can have very different values (and prices depending other factors of the diamond 4C's: Clarity, Color and Cut.

Diamond weight carats Boise Nampa Meridian Garden City Eagle Star Kuna Caldwell Middleton Idaho