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4Cs of Diamonds

The Four Cs At-a-Glance

What are the 4Cs of a diamond---especially when it comes to diamond grading? Peter Yantzer, Executive Director of AGS Laboratories, explains in this quick, informative video. Learn about the different grades on an AGS Labs' diamond grading report, and walk away with a better understanding of what gives a diamond its beauty and quality. This video will give you the information you need to buy a diamond with confidence when you go shopping for that special piece of jewelry!

Need a Primer you can carry around? Download this PDF on the 4Cs, or look below for the 4Cs of diamonds defined:


Of all the 4Cs, cut has the greatest effect on a diamond’s beauty.  In determining the quality of the cut, the 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. Click here for a complete tutorial on the American Gem Society’s patented Light Performance cut grade. Additional information on the cut grade can be found here and also under Education on our AGS Laboratories site. 


Color Gem-quality diamonds occur in many hues. In the range from colorless to light yellow or light brown. Colorless diamonds are the rarest. Other natural colors (blue, red, pink for example) are known as "fancy," and their color grading is different than from white colorless diamonds. To learn more about color grading, click here. Learn about colored diamonds trends.


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. Learn more about diamond clarity and how it is determined


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 of the 4Cs. 

To learn more about carat weight, click here

The Fifth C: Confidence

When you shop smart — with an American Gem Society’s top jewelers — you will feel confident in your decision. You know that the jeweler is qualified to describe the characteristics of your diamond, so you could make the choice that is right for you.

Finding quality diamonds is easy with American Gem Society! Find a certified jeweler near you:

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