A certification is a diamond industry term for a diamond grading report, which documents the diamond's credentials. The certification describes the physical characteristics of a diamond and is usually prepared by an independent grading laboratory. It is a valuable tool for wholesalers, retailers and consumers because it states the diamond's shape, exact measurements and weight, cut parameters, color grade, clarity grade, level of fluorescence, and finish grades.

A diamond certification is only useful if it is reliable and accurate so needs to be issued by a reputable and independent grading laboratory. Not all grading laboratories are created equal so do not expect the grading reports from different laboratories to agree. Some grading laboratories are notorious for being generous in their grading so are very popular with jewelry stores because the reported quality of the diamonds is inflated.

The Gemological Institute of America (GIA) and the American Gem Society (AGS) are recognized in the diamond industry as the most accurate and consistent of the grading laboratories.

A diamond grading report (certification) is very different from an appraisal or other document prepared by someone other than a reputable, independent grading laboratory. For example, there is a big difference between a Diamond Grading Report issued by the GIA and an appraisal or some other documentation signed by a GIA Graduate Gemologist. A GIA Graduate Gemologist is simply someone who has passed a series of diamond and colored gemstone grading courses prepared by the GIA. A GIA Diamond Grading Report is prepared in an unbiased environment, with highly trained GIA Laboratory graders following exacting procedures and using state of the art equipment.

Some unscrupulous jewelers print their own documentation and use names and formats that make them appear similar to GIA documents. These documents can be exaggerated by as much as three color or clarity grades and you can be sure they are off in favor of the jeweler, not the consumer. There is only one reason why a jeweler would use one of these 'copy cat' documents and that is make undeserved profits at the consumer's expense. Inaccurate documentation could affect the value of the diamond by hundreds, thousands or even tens of thousands of dollars so it is important to have a diamond grading report from one of the top grading laboratories when making a diamond purchase decision.

Authentic diamond grading reports never have a value stated. If the document has a dollar value or a range of color or clarity grades (i.e. G-H color, or VS1-VS2 clarity), it is an appraisal not a diamond grading report. It is simply the opinion of the person preparing the document.

Diamond shoppers seeking to purchase a significant diamond, should be sure they have a diamond grading report from one of the major grading laboratories. That is the only way they can be sure of the characteristics of the diamond they are purchasing. It also becomes a valuable document if they ever have to file an insurance claim or sell the diamond in the future. The certification documents the quality of their diamond and provides a way to identify their diamond.