Understanding the 4Cs

The key to understanding diamond quality is to understand color, clarity, cut, and carat, or more commonly referred to as the 4Cs.  These four factors determine a diamond’s value.  This guide will define each of the 4Cs and explain the scale used to evaluate diamonds.


Refers to the presence or absence of color in a diamond.  Diamonds are graded for color on a scale ranging from from D to Z, with D being the highest color grade and Z being the lowest.  Diamonds ranging from D-F are considered colorless, are extremely rare, and are the most valuable.  G-J grades are considered near colorless, while diamonds rated K and below are considered to have a noticeable yellow hue and therefore have a lower value.

Diamond Color

Occasionally deeply saturated colors occur in diamonds such as yellow, brown, orange, pink, blue, green, purple, red, etc.  The most intense of these shades are graded as “Fancy” colors and are graded on a scale separate from the one shown above.


Diamonds are created in nature, therefore the majority will have internal and external characteristics.  These characteristics are termed an inclusion or blemish.  Diamonds are graded for clarity under a 10x microscope.  Clarity grades for diamonds range from Flawless (FL) to Included (I3).  Internally flawless diamonds are extremely rare, and therefore extremely expensive.  The chart below shows the clarity grading of diamonds.

Diamond Clarity


How a diamond has been cut, polished, and to what proportions and symmetry, are of utmost importance as these factors determine the life, brilliance and dispersion of the diamond.  If these cutting factors fall below standard, the appearance of the diamond will be adversely affected.

If a diamond is cut well, light will disperse from the top of the diamond, thus intensifying the diamond’s sparkle.  If a diamond is cut either too shallow or too deep, light will escape from the bottom of the stone, not maximizing the stone’s appearance.

Diamond Cut

Carat Weight

This is the metric used to determine the weight of a diamond.  For a one carat  diamond a scale of 1 to 100 is used.  For example, a half carat diamond would be .50 carat total weight.

Diamond Carat Weight

Content provided courtesy of the International Gemological Institute, the largest independent laboratory for grading and evaluating diamonds and fine jewelry.  With thirty years of experience, IGI provides the jewelry community and consumers with a broad range of services from independent grading reports to laser inscription services.  IGI issues more than one million jewelry reports per year.