What’s The Difference Between GIA, AGS, EGL, & IGI?

Julie Janecka
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Why Is Buying A Certified Diamond Recommended?

The diamond industry isn’t regulated like other consumer goods and therefore seems to be susceptible to scams. You can find a lot of information online, but unfortunately much of it is fragmented or biased. Most big jewelry vendors, on the other hand, have their own certifications, but may be skimping out on telling the full story.

In this post, I’ll try to break down the four major diamond certifications: AGS, GIA, EGL, and IGI, and offer advice on how to read between the lines. Because at the end of the day, it all comes down to what you are looking for and what goes into your budget.


Since both are big players in the industry, it makes sense to compare AGS and GIA, which are the two top competitors in the diamond grading and certification business.

What Are The Most Reputable Certification Labs Around The World?

When it comes to diamonds, you can hardly go wrong when you choose a diamond grading lab that has earned a reputation for superior standards and honesty.

The only issue is, you could spend days trying to figure out which lab is the right choice. There are so many diamond grading labs out there, and they are all listed on the Kimberley Process website, so finding the right lab to use doesn’t have to be a difficult task.

In this article, we’ll take a closer look at the four most reputable labs in the diamond business. We’ll also give you a rundown of their background, what they specialize in, and how to choose the right one to suit your needs. We think you’ll find these diamond grading labs that each have their own unique thing to offer.

Differences Between AGS, IGI, EGL, and GIA Certification Labs?

Many jewelers would like to know the difference between the four most popular gemstone appraisal and certification labs … AGS, EGL, GIA, and IGI. If you’re one of them, here is a clearer understanding.

  • AGS: AGS stands for American Gem Society and was founded in 1987. AGS has its own lab that stores over 100,000 colored stones, which are graded by GIA-trained graders.
  • IGI: IGI stands for International Gemological Institute and was founded in 1971. IGI also has its own lab that stores over 300,000 colored stones, which are graded by GIA-trained graders.
  • EGL: EGL stands for European Gemological Laboratory and was founded in 1968. EGL does not have its own gem lab. Instead, its graders requisition stones from other labs to be certified (tested) at other labs.
  • GIA: GIA is also known as the Gemological Institute of America and was founded in 1931. GIA has its own gem lab, which stores over 6,000 colored stones, which are graded by GIA-trained graders.

Gemological Institute Of America (GIA)

The Gemological Institute of America is one of the most prominent and widely recognized gemological institutes in the world. Its headquarters are located in Carlsbad, California. Its history goes back to 1922 when George F. Kunz, a well-known mineralogist, led a group to establish an independent institution that could research and classify diamonds and colored gems. He wanted to establish a global standard of diamond and gem grading based on scientific principles. Today, GIA is operated by an autonomous board of over 20 members composed of prominent figures in the industry. It is a nonprofit organization that is supported by public contributions and is managed by a self-perpetuating staff.

GIA has the authority to check, grade, identify, evaluate, authenticate, and certify diamonds, colored gemstones, pearls, and jewelry. This is why you will find the GIA diamond grading report, diamond color grading report, diamond luminescence grading report, and diamond clarity grading report on every diamond that is sold at any reputable jewelry store.

Just like any other organization whose primary objective is to set and maintain industry standards, GIA has set and enforced quality control standards. All members of the GIA Laboratories are closely monitored by servicing supervisors, who check for accuracy and consistency when grading gemstones.

American Gemological Society


The AGS was established in 1931 and is one of the most reputed jewelry rating and certification companies. Being one of the oldest as well as one of the most respected gem labs in the world, the AGS is recognized by the American Federal Trade Commission and the United States Customs Service.

The AGS is committed to the education of consumers in the field of gemology. It is the one of the few labs that certifies colored gems. It conducts both educational seminars as well as a regular course, Professional Gem Identification that qualify individuals to become jewelry professionals.

Both IGI and EGL conduct their grading and certification by using the 10-million dollar gem microscope in AGS’s laboratory. The AGS has two international laboratories in New York and Los Angeles that grade and certify most of the diamonds that are used in the diamonds that are used by retail jewelers in the United States. It is one of the few labs that certifies colored gemstones.

What’s the difference?

AGS is a gem certifying lab. It certifies all kinds of gems including diamonds, colored gemstones, and pearls.

European Gemological Laboratory

There are numerous other gemological labs around the world. The one that matters most to jewelers is the European Gemological Laboratory (EGL), the most prestigious gem certification company in the world. In fact, many other labs create their own standards based on the EGL standards.

The closest U.S. equivalent to the EGL is AGS (American Gemological Society). Both of these labs provide their reports to the public for reviews of certification. If you want to make sure your jewelry is legitimate, you can contact either EGL or AGS to verify the certification report.

International Gemological institute

The IGI is a highly respected and independent institute which includes a team of experienced and trained gemologists. The institute was founded in New York in 1976 and since then it has gained wide recognition as experts in gemological analysis. The IGI tests are performed on all kinds of gems including diamonds, sapphires, rubies.

The IGI grading process relies on the 10% and also the 4 C’s determining the value and quality of a gem. 10% refers to the diamonds carat weight which is one of the most important parameters determining the value of the diamond. The 4 C’s are the cut, color, clarity and carat weight of the diamond.

All diamonds are graded in three different color scales:

  • D Diamond
  • E Diamond
  • F Diamond

Additionally, the diamonds are also graded using two different clarity scales:

  • Fl Diamond
  • IF Diamond

IGI provides a certificate with an individual number for every diamond they grade. This certificate is extremely valuable and serves as a guarantee for the buyer that the diamond has been graded according to the IGI standards by experienced and reputable experts.

How To Ascertain If A Diamond Certification Matches With The Specific Diamond?

You might have heard the terms GIA, AGS, EGL, and IGI while shopping for a diamond at a jewelry store. These are very important certification marks for a diamond and each one is graded differently. The important thing to note about these four certification marks is that while each one is different, they are still considered the top standard of the diamond industry.

You might be wondering what GIA stands for. GIA stands for Gemological Institute of America and is the most trusted name when it comes to diamond evaluation and grading. The GIA Certification presentation will show you the weight of the diamond, its cut, clarity, level of color, and carat.

Another diamond certification you should familiarize yourself with is AGS (American Gem Society). The AGS certification mark is not as comprehensive as GIA but does provide an idea of where the diamond is within the grading scale.

You can also buy a diamond with no certification marks or with a different certification if you find it preferable.

What you absolutely must check is if the certification matches with the diamond. Any other certification mark that is used, is irrelevant!

The Difference Between Diamond Certification And Appraisal?

Diamond grading and certification is an imperfect system and it doesn’t ensure you're getting a good deal. With that in mind, here are two quick signs that your stones might not be as fancy as you think:

{1}. The stone is loose in its setting. Diamonds that are loose in their settings are a telltale sign of synthetics. Synthetic diamonds carefully mimic the properties of natural diamonds. To achieve this, they are often made bigger than natural diamonds with very little metal holding them in place.
{2}. The tag attached to the jewelry is low quality. Jewelry tags are an easy way to tell a natural diamond from a cut stone. It’s the little sticker that usually comes with a certificate of authenticity and shows the weight and certification details of the stone. Tags from bigger, reputable retailers are often made to last, but many jewelers will slap an inferior tag on.
{3}. There's a low price tag and big promises. When shopping for loose diamonds, avoid sellers who make a big deal about how cheap the stones are. They are usually trying to drive traffic to their store and don't even have the stones. Sites like Groupon are good at finding this type of seller.

Learn More About Jewelry

This is perhaps the most confusing aspect of gemstones and jewelry. We've all seen beautiful jewelry with certifications, but we don't really know what they mean. Jewelry stores will sometimes even say that one diamond is better than another because of the certification, when in fact, there is no such thing. So who do we believe?

Let’s look at the 4 most common certifications:

  • GIA
  • AGS
  • EGL
  • IGI

If you have done some research online, you’ve probably come across these initials. You may have even seen some of them from time to time, but you have no idea what they are. In this post, we’re going to teach you the difference between GIA, AGS, EGL, and IGI.