IGI vs GIA Diamond Certification

The IGI started out as the blue-collar workhorse of the diamond business. Founded in 1975, the International Gemological Institute (IGI) is the largest of the independent diamond and jewelry certification labs. The IGI started out as the blue-collar workhorse of the diamond business. They are the most popular gem lab for the major jewelry chains in the US and Canada (Kay, Zales, etc.). They are like a factory. They work fast, and their prices are much better than GIA’s.

Historically, IGI has been more lenient in its grading standards than GIA. IGI has made efforts to shore up its grading over the last decade. You will often find stricter standards used in IGI’s USA labs as opposed to those in Europe. Hopefully, they will continue to improve. Until then, I’d stick with GIA. They are still the gold standard in diamond certification.

*Important note: This article is focused on IGI certification for natural diamonds. We will delineate our issues with IGI’s certification, but this is not how we feel about IGI certification for Lab Grown Diamonds. For more information, check out our Lab-Grown Diamond Certificate article.

Here’s what we’ll cover in this article:

What is IGI diamond certification?
What’s the difference between IGI and GIA
Why it’s important to care about a diamond certificate
How honest are diamond companies about certification?
Our experience with diamond grading
Rapnet search to confirm the difference between IGI and GIA

IGI Diamond Certification

IGI bills itself as a top-of-the-line laboratory, but in our opinion sadly that is not the case. While they may not be as terrible as some of the others, we feel that their grading is definitely more lax and less consistent than the standard bearers in the industry. You may be tempted when you see a seemingly fantastic deal like this on Amazon, but its important to dig a bit deeper. 

Even the largest jewelry insurance underwriter writes: “The most reliable diamond certificates (also called diamond reports) come from the Gemological Institute of America (GIA) and the American Gem Society (AGS). These are the most respected labs, known for their accuracy and professionalism. These reports are not appraisals and do not carry valuations. Certificates from any other sources are often questionable and should not be relied upon by insurers.”

Likewise, Dateline raised serious questions about IGI’s integrity in 2005 as pertains to their appraisal values.

We recommend only buying a GIA certified diamond. Only purchase from reputable vendors that sell diamonds certified by this lab (such as Blue Nile & Brian Gavin Diamonds. James Allen does sell IGI certified diamonds as well, but we never recommend those.) The point of buying a diamond with an independent certificate is to get peace of mind that the diamond is the quality they claim. We feel that an IGI certificates do not deliver that.

1) IGI vs. GIA

We decided to put IGI to the test, given all the conflicting reports about their reliability. We purchased five IGI certified diamonds and sent them to the gold standard of laboratories: GIA.

The results were predictable and unfortunate.

IGI inflated the qualities in eight of the ten possible grades (diamond color and diamond clarity on each diamond). Here are the results:

*Click on the carat weight for a video of each diamond. Click on the color/clarity grades for respective certificates.

In our opinion, IGI simply does not function at the standards that reputable diamond laboratories hold themselves accountable to. Now we will explain why this matters to you, the consumer.

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Both of these diamonds have an “SI2” clarity grade.
One of them is certified by EGL,
the other by GIA.
Can you tell which is which?

2) Why Should You (the Consumer) Care About This?

The reason why you must buy a diamond with legitimate certification is to give you peace of mind that the diamond you are getting is the quality the seller is claiming it to be. This allows you to compare the diamond to similar diamonds and make sure you are getting a fair deal.

GIA, the world leader in certification puts it this way: “The GIA Diamond Grading Report is similar to house deeds or vehicle registrations in that it offers information on your purchase, and this information can be used to determine the value of the purchase.”

The problem is that we believe IGI reports don’t deliver on that. In fact, we feel that you are likely getting a subpar deal if someone is selling you an IGI certified diamond. Take a look at these two searches of SI2 and I1 diamonds for comparison:

James Allen Search of SI2 one caraters.

James Allen Search of I1 one caraters.

A typical one carat SI2 diamond will end up costing you around $3,500. A typical one carat I1 (with all the other specs being equal), will cost about $2,500.

So here comes a jeweler who sells diamonds with IGI certificates.

You see an I SI2 diamond for $3,000, so you think “Wow, I’m saving 20%!” In reality though, we feel the jeweler is deceiving you and you are overpaying 20% by using the certificate that inflates the quality claims (based on our and others’ observations).

This is the oldest trick in the book, and it is used by companies to increase their margins while tricking uneducated consumers with less strict certificates.

3) How Diamond Companies Play the Game

I understand and sympathize with people in the diamond industry who have seen the competition grow fiercer and the margins grow slimmer every day. Unfortunately, too many of them have decided to go the route of manipulation and trickery instead of coming up with an alternative way to increase their margins (by providing a unique experiences or special products).

You might think “this is just your opinion, others can have a different one” or “you are cherry picking diamonds for a certain result” but that is simply not true. Diamond companies can, and do, cherry pick the results to use the looser certificates with the maximum grade inflation.

Here is another “trick” they use.

In our experience, some IGI laboratories are weaker than others. Many jewelers in America will say something like “oh, those articles are talking about IGI in Botswana or Mumbai or Antwerp. The IGI lab in NY is much stricter.”

And in a way that is true. Unfortunately, those same jewelers can play a simple trick. What you can do is take a diamond that has an IGI Mumbai (or Botswana, or wherever) certificate, and send it to IGI NY with the certificate from Mumbai.

Then the seemingly stricter IGI lab in NY will give you a certificate and “honor” the grades from their sister laboratory.

In fact, we tested this rumor by sending these same five diamonds to IGI in New York. Three of the diamonds did not have a laser inscription from the IGI labs in Mumbai. Two of them did have laser inscriptions from IGI Antwerp.

We sent the three without inscriptions as “new diamonds” and sent the two that had inscriptions with the certificates from IGI Antwerp. Predictably, IGI New York downgraded the three “new diamonds” from their previous grades from IGI Mumbai, but matched the very generous grades from IGI Antwerp on the other two stones.

What does that tell you about their credibility? What does that say about a jeweler who uses IGI?

Unless this was some miraculous coincidence, IGI New York clearly honored the looser IGI Antwerp’s grades. In what way does doing this help the consumer or their credibility as an independent laboratory?

Legitimate laboratories do not let anything influence their grading (GIA ignores any markings you put on the packaging other than your own SKU number and weight, certainly wouldn’t let you tell them the grades of another GIA laboratory in hopes of influencing their decision).

Even though the industry knows about this trick, we were still surprised it worked so easily, so we decided to do an IGI report check again – this time with a more precise methodology.

This time, we took 4 diamonds already certified by IGI New York and we sent them to IGI Antwerp for certification as uncertified new diamonds. After getting the results, we sent these diamonds back to IGI New York with the Antwerp certificates attached (with the intention to influence the new grades). IGI New York was not made aware of the original IGI New York certificates that we had made.

Below are the results of our experiment:

On the one hand, it’s refreshing to see that IGI New York didn’t stoop so low as to match the ridiculously upgraded grades from Antwerp. On the other hand, they were clearly influenced by the accompanying Antwerp certs. Each stone received at least one upgrade on their IGI report.

4) Reviewer’s First-Hand Experience

I know this particularly well, as throughout my professional career, we (myself and Ira, the founder of this site) must have personally selected thousands of diamonds to be sold as IGI SI2s at the major jewelry store chains in the US and UK.

These programs (usually the middle-ground price point offering great value as it’s the cheapest of the eye-clean grades) all have a minimum of SI2 clarity.

For these programs, we would always strive to find diamonds that were in that “SI3 clarity” sweet spot — diamonds that would not receive an “SI2” from GIA, but were too nice to sell as an “I1.” This is our opinion based on years of experience.

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Feb 1, 2023

5) And if You’re Still Not Convinced

On Nov 3rd, 2016, I performed a search on Rapnet (the world’s largest online market for wholesale diamonds – think the NYSE for diamonds) using their TradeScreen™ tool. This tool allows you to get a snapshot of average market asking prices for specific parameters.

I limited my search to 1 carat “triple excellent” round diamonds with no fluorescence. One search I did using only GIA certified diamonds and the other search I limited to IGI certified diamonds.

See the results below:

Taking the average of the differences of all of these specific color/clarity combinations (weighing each coordinate on the matrix equally), leads to the conclusion that GIA certified diamonds are 18.77% more expensive than IGI certified diamonds on average (at least for 1.00-1.49ct diamonds).

In financial economics, the efficient-market hypothesis states that asset prices fully reflect all available information.

I feel there is only one logical explanation why the wholesale diamond market would price in such an enormous discount in IGI certified diamond prices when compared to GIA certified diamonds: the “market” believes IGI’s grades are inflated when compared to GIA’s.

If you would like to know more about the best diamond certifications, read our guide on diamond certificates.

Here are more specific certificate topics to browse:

• What diamond certification is the best?
• What is the meaning of GIA diamond certification?
• How does AGS certification compare vs. GIA?
• How does EGL certification compare vs. GIA?
• How does HRD certification compare vs. GIA?
• Is GSI diamond certification good / how does it compare vs. GIA?
• Does GIA or IGI certify lab-grown diamonds?

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About the author

Mike Fried Mike Fried has over 25 years experience in the diamond industry working with Leo Schachter Diamonds, Moshe Namdar Diamonds, and joining The Diamond Pro in 2007. He is recognized as an industry expert and has been quoted in publications such as Us, People, Page Six, The Next Web and more.