What Is The Difference Between IGI and GIA Diamond Certificates?

If you have been looking at diamonds online, specifically at James Allen you may have noticed that diamonds come graded by GIA, IGI, and AGS.

And perhaps you have been asking yourself “Should I buy an IGI graded diamond?”

They are often a little cheaper which makes some people view this with suspicion.

However, as this article will demonstrate, there’s no need to shun IGI graded diamonds.

An Unfortunate Consequence of Competitive Pricing

The problem IGI has had with their reputation is sadly a consequence of being cheaper. The stain on their reputation was an unfortunate consequence of charging less!

Since IGI diamond grading certificates cost less than GIA certificates this resulted in lower quality stones being sent to IGI for grading rather than to other labs such as GIA.

The IGI graded stones were therefore automatically deemed by jewelers to be inferior from the time they got them. And of course their suspicions continued to be confirmed as most of the IGI stones they had been getting were inferior.

The Big Change

When lab created diamonds began to become more widely available many in the diamond industry were slow to embrace the change.

It was at this stage that IGI made a very smart decision.

IGI accepted lab grown diamonds and began grading a large amount of these new stones. This resulted in IGI getting a huge influx of work when few other grading labs were accepting lab grown diamonds.

Over the few years that IGI was ahead of the others and benefiting from the increase in business they began to show their standards aligning more and more with the results provided by other gem grading networks.

The improved the consistency across the IGI network did not go unnoticed.

The big fear anyone has when buying a diamond is that the diamond has been overgraded. This results in a higher price being paid for the stone than would otherwise be the case.

A Direct Comparison

A few weeks ago ADA Diamonds conducted an experiment to find out if there was a big disparity between IGI and GIA by having a set of good quality lab created stones be subjected to grading by both labs.

They found that both labs were surprisingly close in how they graded the stones.

IGI or GCAL CertificationGIA Certification
LG11195202 3.02ct E VS1 Oval2215227848 3.02ct E VS1 Oval
LG302600039 2.76ct D VS1 Oval1216223694 2.76ct D VS1 Oval
LG432031489 2.51ct E VS1 Oval6213223703 2.51ct E VS1 Oval
LG302250035 2.30ct D VVS2 Oval6214223701 2.30ct D VVS2 Oval
LG291700030 2.10ct G VS2 Pear1216228122 2.10ct F VS1 Pear
LG414062955 2.09ct F VS1 Pear2215223700 2.09ct F VS1 Pear
LG400913730 2.06ct G VS1 Oval6214228039 2.06ct G VS1 Oval
LG302200028 2.05ct D VVS1 Cushion6214223696 2.05ct D VVS1 Cushion
LG301890313 2.02ct G VS2 Radiant6217223698 2.02ct G VS2 Radiant
LG407986975 2.01ct E VS1 Oval407986975 2.01ct D VS1 Oval
LG302300035 1.85ct F VS2 Oval2215223709 1.85ct F VS1 Oval
LG291820124 1.71ct G VS1 Emerald2215228048 1.71ct F VS1 Emerald
LG414077300 1.67ct D VVS2 Emerald2215223712 1.67ct D VVS2 Emerald
LG291210071 1.59ct F VS2 Oval5212223705 1.59ct F VS1 Oval
LG400998692 1.54ct F VVS2 Emerald2215223704 1.54ct F VS1 Emerald
LG302050043 1.54ct F VS2 Oval2215227544 1.55ct F VS1 Oval
LG302440001 1.17ct D VS1 Ideal Round2215223790 1.17ct D VS1 Excellent* Round

ADA Diamonds also sent a batch of stones to both IGI or GCAL and AGS to find that the results, again were extremely close.

Original IGI or GCAL certificationAGS Report of the same diamond
LG11591102 1.03ct F VS2 Ideal RoundLG404051599004 1.03ct E VS2 Ideal® Round; 0
LG301700108 1.12ct E VS2 Ideal RoundLG404051599001 1.12ct E VS2 Ideal® Round; 0
LG302050216 1.55ct E VS2 Ideal RoundLG404051604003 1.55ct E VS2 Ideal® Round; 0
LG302470007 1.62ct D VVS1 Ideal RoundLG404051602005 1.62ct D VVS1 Ideal® Round; 0
LG11630601 1.63ct F VS1 Ideal RoundLG404051602004 1.63ct F VS1 Ideal® Round; 0
LG365965521 1.80ct H SI1 Ideal RoundLG404051605006 1.80ct G SI1 Ideal® Round; 0
LG302300002 2.22ct F VS2 Ideal RoundLG404051604002 2.22ct F VS2 Ideal® Round; 0
LG302470014 2.83ct D VS2 Ideal RoundLG404051602003 2.83ct D VS1 Ideal® Round; 0
LG11311116 3.08ct G VS2 Ideal RoundLG404051602002 3.08ct G VS2 Ideal® Round; 0
LG11564311 4.18ct E VVS1 Ideal RoundLG404051605001 4.18ct D VVS1 Ideal® Round; 0

Note: AGS grading these lab grown diamonds was part of an AGS pilot program. At present AGS is not yet accepting lab grown diamonds en masse.

While the above examples are lab grown diamonds the technology used to grade earth diamonds is the same so the ongoing results produced by these labs should be expected to also match the above results whether lab grown or earth made diamonds are being graded.

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4 Responses

  1. Chrales Xavier says:

    Thank you for a very informative article. I can see you put a lot of thought into it.

  2. Charlie says:

    Interesting article. thanks.

  3. C.J. says:

    Hello there I am so happy I found your site, I really found you by accident,
    while I was researching on diamonds, Anyways I am here now and
    would just like to say kudos for a fantastic post and an all round interesting blog.

  1. August 6, 2021

    […] wrote an article yesterday about how little difference there was between IGI and GIA grading reports issued for the same set of lab created diamonds. At present most lab created diamonds are graded by […]

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