When purchasing certified diamonds it is important to understand the diamond grading criteria used by the labratories performing the certification as well as the differences between the many laboratories.

Diamond grading covers numerous aspects of each individual diamond's qualities, but there are four grades which are critical to understand: cut, clarity, color, and carat weight. There are additional ratings and measurements noted on a diamond certificate, but they generally fall under the diamond's grade in one of the Four Cs. For example, measurements listed such as "depth" and "table" are part of the description of the diamond's cut .

You can learn more about how diamonds are graded by reading the articles listed below or you can test you existing knowledge by taking our diamond grading quiz

Diamond Cut

Cut is probably the most important quality factor, and most challenging, of the four Cs to understand. The brilliance of a diamond depends heavily on its cut.

Diamond Clarity

Most diamonds contain some inner flaws, or inclusions, that occur during the formation process. The visibility, number and size of these inclusions determine what is called the clarity of a diamond. Diamonds that are clear create more brilliance, and thus are more highly prized, and priced.

Diamond Color

Colorless diamonds are the most desirable since they allow the most refraction of light (sparkle). Off white diamonds absorb light, inhibiting brilliance.

Carat Weight

A carat is the unit of weight by which a diamond is measured. Because large diamonds are found less commonly than small diamonds, the price of a diamond rises exponentionaly to its size.  As diamond weight increases, it's size increases but since the diamond increases 3-dimensionally it's diameter, or visual appearance, will not increase at the same rate.

Example: While a .50 Carat Diamond measures 5.2MM, a 1.00 Carat Diamond measures 6.5MM  - (Assuming proper proportion/cut)

The Fifth C: Certificates

The diamond certificate, which is sometimes called a grading report, is a complete evaluation of your diamond that has been performed by a qualified professional with the help of special gemological instruments. Each stone bears its own recognizable, individual characteristics, which is listed on the certificate. 

Understanding the differences between the many tpyes of certificates, and many laboratories doing certification, is as important as any of the other C's.