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Facts About Diamond Grading Reports
 Each diamond is unique in its character and quality, thus prices can vary significantly from stone to stone. So before you spend money, it is crucial to know what you are buying. A diamond grading report (also called certificate) done by a professional grading institution will provide such information as well as proof of authenticity of the stone. In the mean time, different grading companies grade diamond differently. Some use stricter standards than others. So, it is also very important to understand the difference between grading companies and the reports they generate which we will explain as follows.

What is a diamond grading report (certificate)?
A diamond grading report is a report created by a team of gemologists.  It is also called a diamond certificate, diamond dossier, or diamond quality document, depending on different gemological institute.  During the grading process, the diamond is weighed, evaluated, measured, and scrutinized using professionally trained eyes, a jeweler's loupe, a microscope, and other industry tools. A completed certificate includes an analysis of the diamond's carat weight, clarity, color, polish, symmetry, dimensions and other characteristics. Round diamonds also include a cut grade on the report while diamonds of other shapes do not. Below are some sample reports from the leading diamond grading institutions.

GIA Diamond Report AGSL Diamond Report EGL USA Diamond Report IGI Diamond Report

What are the major diamond grading institutions?

There are several major diamond grading institutions in the world: Gemological Institute of America (GIA), American Gem Society Laboratories (AGSL), European Gemological Lab (EGL), International Gemological Institute (IGI).  EGL also has several independent labs around the world: EGL USA, EGL International, EGL Israel, EGL India, etc. 


GIA Gemological Institute of America, head quarter located in Calsbad, CA, was founded in 1931. It is regarded as the world's foremost authority on diamonds, colored gemstones and pearls by using the strictest standards in terms of grading. It is considered the bench mark in diamond grading. Many diamond dealers use only GIA to grade their diamonds to ensure the highest grading accuracy.


AGSL American Gem Society Laboratory is located in Las Vegas. It is affiliated with American Gem Society which was founded in 1934 by a group of independent jewelers. It is the first grading company that gives cut grade not only on round diamonds, but also on fancy cut shaped diamonds, such as princess, oval and emerald cut diamonds. It has earned its reputation as one of the top diamond grading laboratories in the world from its accuracy, consistency and thoroughness in its diamond grading operation.


EGL USA, headquartered in the heart of diamond and jewelry district in New York City, was originally part of EGL (European Gemological Laboratory), an international network founded in Europe in 1974. It became independently owned in 1984 and is not affiliated with any other EGL labs outside of North America. It is ones of the largest and oldest institutions focusing on gemstone reseach and certification.


IGI International Gemological Institute was founded in Antwerp, Belgium in 1975. Today, with offices throughout the world, it is one of the largest diamond and color gemstone grading institutions in the world.

Why are GIA certified diamonds more expensive given the same characteristic of the diamond?
If you have spent some time looking for a diamond and come cross several diamonds certified by different grading companies, you might be surprised to find that diamonds certified by GIA are often more expensive than those certified by other companies with the same listed characteristics. The explanation is that different grading institutions use different grading standards. As a result of GIA's strict grading standards, GIA certified diamonds are of higher quality than diamonds graded by other institutions with the same listed characteristics. The leniency by other grading institutions is most often reflected in the color grading and sometimes in the clarity grading.  In mostly cases, the color can be off 1 to 2 levels and the clarity can be off 1 level. The difference in the quality results in the difference in pricing.

What is the difference between a Diamond Grading Report and an Appraisal?
A  Diamond Grading Report is a document issued by an independent institution such as a gemological laboratory describing various characteristics of a loose diamond. An appraisal is usually done by an in-house or an independent gemologist indicates the characteristics of the diamond along the Dollar Value of the piece under consideration. Appraisals are most often used for insurance purposes.

Many people make the mistake of using an in-house appraiser to evaluate the purchase price of their Diamonds. First, appraisals are often over-estimated, and are therefore a very poor estimation of price. More importantly, any in-house Jeweler may be biased towards their own merchandise. Further more, Many consumers assume that getting an appraisal by a GIA graduated gemologist is the same as getting a GIA Grading Report. Some unscrupulous Jewelers attempt to further that illusion. Many Ebay sellers sell diamonds that are appraised by themselves and make buyers believe that they are the same as those graded by a major institution.  While many sellers stay true to their statements, a lot of them intentionally inflate the value of their products. 

How to buy a diamond on ebay or on line in general?
First, do your research before you buy.  There are many good online resources that you can use to learn about diamonds.  We have a basic page called "Diamond buying guide" that gives you a good idea of what you need to know before you invest any money on a diamond. 

Second, find a reputable seller with good ratings.  Read about their feedbacks, especially negative feedbacks. This way, you can see why people are not happy with the diamond they purchased.  If several customers say that the seller is using deceptive descriptions, the alarm should ring.

Third, make sure that the diamond is graded by a reputable institution, not by an in-house appraiser.  This way, you can make sure that the opinion on the diamond is not biased and the value not inflated. If you really want a good quality diamond, you should look for a GIA certified diamond.  At TADragon, we offer a huge selection of GIA and some EGL USA certified diamonds to make sure that the quality of the diamonds stay true at all time.  We have educated many happy customers and will continue to do so in the future. 

If you have any questions regarding pearls, you can call TADragon at 805-277-7232 or email us at