How to Read Diamond Grading Reports

A diamond color rating chart

Diamond grading reports are used to describe diamonds in great detail. You will probably need one in order to insure your diamond and most jewelers recommend that you get one when you make a major diamond purchase in order to be sure that you understand what you are getting. Diamond grading reports describe the color and other aspects of the diamond that play crucial roles in determining the stone's value. However, they go into much more depth than the traditional "Four C's" lecture that you will get when you enter any jewelry store and actually address how these qualities impact the diamond's value on a very individual and specific level.

Instructions

1. Evaluate the lab that issued the report. Depending on how you want to buy the diamond, you may need to get a report issued by one of multiple labs. For example, AGS (American Gem Society) diamond quality reports are popular with online buyers because their "sight unseen" descriptions and reputation are among the best in the business. However, if you are buying the diamond in person and therefore able to factor in your own impressions and just need to make sure that you are not being sold a low caliber diamond in the guise of a high-quality stone, then you may prefer an EGL (European Gemological Society) or IGI (International Gemological Institute) report, both of which are common in stores and a bit easier to read. If you are buying diamonds abroad, the most ubiquitous and respected company is the Belgian HRD based in Antwerp.

2. 

   Look for the letters. One of the most important pieces of information in a diamond grading report is the color grade. This grade is a letter and can be anywhere from D to Z. Anywhere between D and F means the diamond is virtually colorless, which can make the value of a stone significantly higher even if it is not as big as another stone. G through I diamonds have very little color and can be cut to sparkle with nearly as much if not equally as much fire as a clearer stone, and J through L stones have a yellowish tinge. A diamond may have a letter rating farther into the alphabet, but these diamonds are generally of very poor quality because they neither sparkle nor have a pretty color. However, as a diamond's color rating verges on Z, the value increases dramatically.

3. 

   Double check the comments area. This is the area where issues with clarity or other types of "intangible" objections or kudos will be listed. For example, if a diamond has a strange flaw that makes it flash magenta when you hold it up to the light, that may not make it onto the inclusions list as a positive but the evaluator might mention the unique aspect in the comments section. Similarly, if a diamond is just perfect from an analytical standpoint but somehow fails to measure up aesthetically, then the comments section will be used to point this out.

4. 

   Look for anomalies. While you probably know that you should be interested in cut, color, carat and clarity and you may already know something about how to decide if you like these aspects of a diamond, these are not the only things included in a diamond grading report. Also important are treatments that a stone has undergone, if it has been laser inscribed, and a plotting diagram of inclusions that will help you identify a diamond from any other. These are the types of information that you should focus on when you read a grading report as they are frequently not available from the vendor or selling jeweler.

5. Consider fluorescence. Some people like their diamonds to fluoresce slightly under certain types of artificial lighting and even in sunlight. A diamond that fluoresces may appear brighter in certain environments, but if you have a colored stone the fluorescence may actually cause the color to look muddy. Information about a diamond's level of fluorescence and the impact on the look of the stone should be available in a diamond grading report.

Tips & Warnings

• If you are not a certified expert, enlist the help of an independent, licensed jeweler to help you understand your diamond grading report before you make a purchase.