Diamond certification is essential when buying a diamond and is different from a jeweler's appraisal, although the certification is part of any appraisal. Many diamonds look the same, but not all of them will be of the quality you might like. Diamond certification is the written proof of a diamond's attributes. With it, you know the precise grading for each 4Cs – color, cut, clarity and carat weight, and, therefore, the diamond value. Without it, you are not assured that the diamond you buy is of the quality you're paying for.

Certification gives you the information you need to assess a diamond's value compared to other diamonds. It also allows you to make an intelligent comparison with diamonds in the same jewelry store or in another.

Diamond certificates are issued by independent gemological laboratories, not your jeweler. There are several grading laboratories, the most prominent being: the International Gemological Institute (IGI); the Gemological Institute of America (GIA); the American Gem Society (AGS); the European Gemological Laboratories (EGL), and GemEx Systems.

When you buy a diamond, be sure to question the sales associate first about the characteristics or attributes of the stone. Ask to see the diamond certification that will accompany the diamond when you purchase it. If you do some comparison shopping, you will note that the quality of the diamonds each jeweler carries varies depending on the store.

A diamond certification will also give you indicators about other diamond qualities, such as fire, brilliance, and scintillation, also called Return of Light. These qualities refer to how light is refracted back to the viewer when held stationary or when in motion. The certification will also give you a measure of the stone's fluorescence. These factors also impact the beauty and brilliance of your diamond.