Diamond Grading Certificates - What's the difference between GIA, AGS, IGI and EGL?
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Shopping for the perfect diamond engagement, wedding or anniversary ring is no easy task. That’s why having a trusted jeweler like Ben Garelick who has been in the business for decades on your side is a great start.
Still, you may want to educate yourself not only about the well-known “4 Cs” of diamond quality - cut, clarity, color, carat weight, but also about the type of grading certificate that may accompany the diamond.
There are many grading laboratories and gemological institutes around the world that may give credence to the ratings that make up some of those “Cs,” but not all laboratories are created equal.
Each of these certificate issuers uses their own grading method and terminology. And that makes it even more difficult to make sure you are getting the quality of diamond that you are paying for.
What one certificate claims as “high-quality” may not be consistent with what another certificate claims.
The solution to overcoming this challenge is to learn a little more about what a grading report shows and the four best known gemological labs in the world that issue the certificates that you may encounter.
In this article...
What is a Diamond Grading Report?
A Diamond Grading Report records in detail the particular qualities of a loose diamond or gemstone. It confirms the stone’s authenticity and quality. It is not an appraisal, which is usually used for insurance purposes to verify jewelry value but it can be a document that you can use to prove ownership.
Although it’s described in varying terminology, the grading report will include a range of values for the diamond’s brilliance, cut or shape, any known treatments to the color or clarity of the stone, any inclusions, and carat weight.
As you evaluate diamonds or gemstones for the perfect diamond solitaire engagement ring, a grading report will give you an in-depth explanation of the quality of the stone and ensure you aren’t scammed by a treated or synthetic diamond.
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That’s why a grading report can be critical in figuring out if you are paying what the diamond is worth. Buying a diamond from a jewelry store that offers a third-party grading certificate is critical to avoid a conflict of interest or bias in the grading.
However, it’s important to keep in mind that this explanation is a subjective opinion and that’s why it is important to know where the grading report originated. Here is a snapshot of the four biggest diamond grading laboratories in the world.
Top Four Diamond Grading Organizations
1. Gemological Institute of America (GIA)
The GIA is the leading gemological laboratory in the world and one of the industry’s most respected and trusted service.
The GIA has operated for more than 85 years with its headquarters currently located in Carlsbad, California. In the 1940s, GIA established the “4Cs” and the International Diamond Grading System™ – to this day, the worldwide standard for evaluating diamond quality. It has offices in cities around the world and employs more than 1400 scientists, educators, and certified diamond graders.
The reports issued by GIA are highly respected for their stringent grading criteria and demonstrated consistency. Purchasing a diamond or gemstone with a GIA report should give you the best representation of your diamond’s true quality.
2. American Gemological Society (AGS)
Also headquartered in the U.S., the AGS was formed at about the same time as GIA with the focus as a trade association of jewelry retailers, independent appraisers, suppliers, and other industry members. Members of the AGS subscribe to a high level of ethics especially with regards to education and consumer protection.
The grading system used by AGS is similar to GIA and equally respected as a high-quality report. Instead of using an alphabetical rating system, AGS uses a scale of 0-10 for rating a diamond’s characteristics, with 0 as the best and 10 as the worst. Most consider that in comparison, the AGS grading report provides more in-depth information related to the cut quality and light performance of the diamond.
This is because AGS reports assess cut quality on a stricter standard compared to GIA using an optical ray-tracing assessment which measures the light performance of the diamond.
To compare the AGS grading terminology with the GIA’s: if a jeweler tells you that a diamond has an AGS cut grade of 0, clarity grade of 3 and color grade of 2.5, the equivalent on the GIA scale is a diamond with Excellent cut, VS1 clarity and I color.
3. International Gemological Institute (IGI)
The IGA is based in Antwerp, Belgium and is the second most well-known gemological lab in the world after GIA. IGI takes advantage of having its headquarters in the “loose diamond capital of the world” and grades a notable number of loose polished diamonds in the world market as well as synthetic diamonds. IGI offices can also be found across Asian countries and they maintain offices in major U.S. cities as well.
For grading reports, IGI reports are often considered less consistent with lower standards than GIA reports. The IGI had been the fast-working go-to evaluator for major U.S. chains like Kay and Zales, but test after test, jewelers found that IGI inflated the qualities of the diamonds they graded.
For example, in this test, for two diamonds of the same carat, color, and clarity grade, an IGI certified diamond is on average 12% cheaper than a GIA certified diamond. Because of this inflation of quality by the IGI, the IGI diamond may actually be a lower quality diamond, even though “on paper (the certificate)” states it as the same quality as the GIA diamond.
Therefore, the pricing will appear to be less expensive on the IGI graded diamond, but since the two diamonds are not actually the same quality, the IGI diamond will be offered at a better price.
4. Euorpoean Gemological Laboratory (EGL)
This European-founded grading organization has a huge global presence with locations in all the biggest cities around the world. EGL is most known for its groundbreaking diamond grading methods for diamonds and gemstones weighing less than a carat. The EGL is a for-profit entity, unlike the GIA and AGS.
In grading, most jewelers believe the EGL operates under lower quality standards that the GIA, meaning the value of a diamond might appear overinflated. In fact, a few years ago, the EGL was entangled in multiple consumer lawsuits for over grading diamonds.
EGL is also known for creating a new rating called Sl3 for clarity in the 1990s which most agree was an unnecessary addition used to fool diamond buyers into thinking they were purchasing a higher-quality diamond.
The Bottom-line Of Diamond Grading Certificates
Reputable jewelers with longstanding reputations and satisfied customers will never offer you an IGI or EGL certificate as proof of diamond quality. Stick with diamond sellers like Ben Garelick Jewelers when purchasing your next diamond engagement or anniversary ring or pendant.
Ben Garelick offers only GIA certified diamonds because we care about getting you the highest quality diamond for the best price. We offer your choice of center diamond in all of our stunning designs by the best designers in the world like Kirk Kara, Simon G., and Gabriel.
Plus, we can custom-design your engagement ring to make it as individual as your love. As always, if you have questions about purchasing a diamond or about certifications, please reach out to us by text at (716) 574-0966, by phone at (716) 631-1584, or online.
Or visit our Buffalo, New York, jewelry store for face-to-face assistance. We value our customers and look forward to helping you find an unforgettable diamond for the one you love.