Understanding the Four Cs of diamonds

Meet the Four Cs

Gemstone value is based on a combination of features, sometimes called value factors. As with other gemstones, diamonds with certain qualities are more rare and more valuable than diamonds that lack them. Without a systematic way to evaluate and discuss these factors, there would be no way to compare one diamond to another. 

Diamond professionals use a special set of four value factors to describe and classify diamonds: Color, Clarity, Cut, Carat weight. These are knows as the 4Cs. When used together, they describe the quality of a finished diamond, which is directly related to its value. 


People outside the diamond trade often misunderstand the relationship between diamonds and color. Many people think of diamonds as colorless. In reality, truly colorless diamonds are quite rare. Most diamonds used in jewelry are nearly colorless with yellow or brown tints, most often light yellow. Diamonds come in many colors other than yellow and brown, called fancy color diamonds. Some of the most rare colors are red, purple and green. With colored diamonds, more color usually means higher value. The GIA D-to-Z color grading scale is the industry's most widely accepted grading system. 




Diamonds might have internal features, called inclusions, and surface irregularities, called blemishes. Together, they're called clarity characteristics. Clarity is the relative absence of inclusions and blemishes. Among other things, blemishes include scratches and nicks on a diamond's surface. inclusions are on the inside, or they might extend into the interior from the surface of the stone. Although, clarity characteristics might have negative influences on diamond's value, but they can also help to identify individual stones. They also provide valuable information about how diamonds form. 

Blemishes have less impact on a stone's beauty and value, they're relatively easy to remove. Clarity's influence on value is directly related to the concept of rarity. Flawless is the top grade in the GIA clarity grading system, they don't have visible inclusions or blemishes when examined under 10x magnification by an experienced grader. 

The GIA clarity scale has six categories:

  • FLAWLESS (FL) no inclusions - no blemishes
  • INTERNALLY FLAWLESS (IF) no inclusions - minor blemishes
  • clarity
  • VERY VERY SLIGHTLY INCLUDED (VVS1-VVS2)  minute inclusions, difficult to see 
  • VERY SLIGHTLY INCLUDED (VS1-VS2) minor inclusions, difficult to somewhat easy to see
  • SLIGHTLY INCLUDED (SI1-SI2) noticeable inclusions, easy to very easy to see
  • INCLUDED (I1-I2-I3) obvious inclusions, visible and easy to see



    A well cut diamond can make light perform in breathtaking ways, resulting in a magnificent display of three important diamond attributes: brightness, fire, scintillation. 

    Brightness, sometimes called brilliance, is the combination of all the white light reflections from the surface and the inside of a diamond. Fire is the word for the flashes of color you see in a polished diamond. Scintillation describes the flashes of light and contrasting dark areas you see when the diamond, the light, or the observer moves. 

    The three major parts of a polished diamonds are the crown, the girdle, and the pavilion. The polished surfaces on the crown and pavilion,  and sometimes girdle, are called facets. Some polished diamonds also have a flat facet at the bottom of the pavilion, called the culet. The term brilliant cut is used as a general term for gems of any shape with facets that are mostly triangular or kite shaped and that radiate from the center. The standard round brilliant is by far the most popular diamond cut which has 57 or 58 facets. Shapes and cutting styles other than the standard round brilliant are called fancy cuts. The most familiar are the marquise, princess, pear, oval, heart and emerald cut. 



    Carat Weight

    Carat weight is the measurement of how much a diamond weighs. A metric carat is defined as 200 milligrams, and each carat can be subdivided into 100 'points'. This allows very precise measurements to the hundredth decimal place. The weight of a diamond below one carat can also be described by its points alone. For instance, a diamond that weighs 0.25 carats could also be referred to as a 'twenty-five pointer'. All else being equal, diamond price increases with carat weight, because larger diamonds are more rare and more desirable. But two diamonds of equal carat weight can have very different values depending on three other factors within the 4Cs. 



    Source: Gemological Institute of America