Skip to Content

Is GSI Better Than IGI?

Is GSI Better Than IGI?

When purchasing a diamond, a grading report must accompany that gem. That’s imperative for diamond shopping. 

However, there are plenty of diamond grading labs, and it can be pretty overwhelming to decide which one you should trust. 

The two labs that are generally talked about when it comes to diamond grading are GSI and IGI. So, the question is: Is GSI better than IGI? Or is it the other way around?

Truth be told, both of these labs come pretty close regarding their grading methods. But what is diamond grading? And what are the best diamond grading labs while we’re at it?

Don’t worry; answers to these – and many more – questions are covered in this guide. So, keep on scrolling! 

What Is Diamond Certification?

Diamond certification is a third-party-issued document you receive that describes the stone in all of its characteristics.

Along with each stone you’re considering, you should receive – and then carefully review – its lab certification. A third-party grading entity will issue this lab certificate or report, describing various factors of the diamond – such as cut, carat, color, and clarity.

It’s worth noting that each lab grades and describes diamonds differently, and sometimes, these differences may be significant. Since there are several diamond grading labs, you should know which ones are reliable and trustworthy – and which aren’t.

Because diamond reports aren’t created equal, the value and price of gems aren’t comparable across varying lab reports, either. Be sure to buy a diamond with a lab certificate from a highly reputable grading lab.

Also, be sure to review the diamond closely before you purchase it – and see if it aligns with the things mentioned in the report.

Related Read:

What To Watch For In Diamond Certificate

Here’s what to remember as you compare different diamond certificates. 

Consistency Comes First

When it comes to comparing grading entities, it’s much more important to watch for grading consistency than the strictness of grading methods.

For instance, the GIA won’t grade a stone the same way the IGI grades it

The reliability of the gem’s color and clarity grade is only as good as the grading lab’s reputation. But if one grading lab consistently gives a single clarity or color grade higher than the other, that lab is less authentic.

To highlight the importance of this problem, as an example – color grades: You decided to go for an H-color diamond. While you think you’ve found a deal, picking up the H color diamond with an IGI lab report, you notice that a diamond has a yellow tint when you come home.

To your disappointment, the diamond turned out to be an I color by the GIA’s standards, which means the IGI offered an invalid certificate.

Remember to look for consistency within the lab’s grading decisions – rather than just comparing grades between certificates.

Diamond Grading Is Subjective

All diamond grading is subjective. Contrary to popular belief, there’s no central organization that defines an SI1 clarity or G color diamond and their respective appearances.

If one grading entity consistently calls one color diamond color grad G and the other consistently calls the same diamond color H, it’s perfectly reasonable and acceptable – as long as these labs do it consistently.

But it’s also vital to note that even when a lab is consistent in its diamond grading, that doesn’t necessarily mean the lab is trustworthy and reliable. 

Purchasing a diamond with a not-so-reliable certificate at a higher price tag is not prudent, even if the grading lab consistently grades stones this way. You aren’t receiving the value for the price you’re paying.

Considering The Price Over Lab Report

Regardless of the lab report you get, you should heavily assess the price of the diamond. The price should reflect the diamond’s true beauty and quality – both on paper and to the naked eye.

If you aren’t sure if a stone is priced correctly, be sure to have a professional review it for you before making a purchase.

Different Certification Labs Provide Different Results

Keep in mind that every lab has its quirks. Some are looser in grading clarity, while others are looser in grading color. Some labs will always upgrade certain color ranges, while others favor specific arrangements of inclusions.

And smart diamond companies know how to use this knowledge to maximize their results. 

Knowing which labs are reliable and consistent will help you make the right, informed decisions when purchasing a diamond. You’ll avoid buying a stone worth less than what the certificate is stating to be true.

What Are The Best Diamond Certifications?

The best diamond certifications you can get are issued either by the GIA or AGS – these are the most consistent diamond grading entities. That means that you can trust their grading methods in all aspects – cut, color, and clarity. 

These labs also grade more strictly compared to other diamond grading labs. When a diamond is accompanied by the GIA or AGS grading certificate, you can most certainly trust what the report is showing.

That’s why we only recommend purchasing diamonds with either of these two certificates.

GIA Certification

The Gemological Institute of America (GIA) is the most renowned and well-respected diamond grading entity. Their labs are incredibly consistent and provide the greatest peace of mind when it comes to purchasing any diamond.

GIA has no financial stake when it comes to diamond sales and assesses diamonds on several qualities and factors, which include:

GIA has a reputation for grading clarity and color – the most subjective scales – more strictly than others.

Since GIA has a high reputation and proven consistency, we strongly recommend purchasing diamonds that come with their certificate.

Related Read: Is GIA Better Than HRD? The Differences & The Similarities

AGS Certification

The AGS prides itself on being the first lab to provide diamond cut grades. Interestingly enough, long before the GIA introduced their famous cut grade, the AGS has been providing its distinct cut grade scale from 0 to 9.

The AGS had a monopoly on diamonds with “ideal cut” back then. A diamond couldn’t be called ideal without an AGS certificate to back up that claim. 

Now that the GIA has provided its own cut grade scale, AGS’s share in the diamond market has dropped drastically.

The AGS generally tries to market itself as more fancy and refined than the GIA and the rest of the diamond grading entities. 

But in reality, there’s hardly any difference between the two labs.

Still, AGS is the go-to choice for many retail jewelry shops selling perfectly cut round stones.

The one problem to look out for is so-called upgrade shopping: You see, no diamond grading lab is 100% accurate as clarity and color aren’t objective grades. If a stone falls between two grades, a diamond producer or retailer could send it to multiple labs looking for a better score.

For instance, say a diamond is intense J color or weak I color, and it received a J color from the GIA. The retailer may send that same gem to AGS for the I color grade since they can sell it for more money with that color grade.

Color grades will likely be the same, but still, there’s a possibility that the diamond will get the upgrade.

It’s common to see companies using AGS for branded super ideal stones like Hearts on Fire and True Hearts. However, AGS isn’t as commonly used for non-round diamonds.

Here’s an example: If a retailer has 100 cushion-cut diamonds, 98 of which are GIA certified and 2 AGS diamonds, those two stones are most likely to have gotten an upgrade.

Don’t get us wrong; this isn’t a knock on AGS. 

Instead, it’s a mere observation of how some retailers and wholesalers try to take advantage of the consumer. 

All in all, AGS is also a reliable and trustworthy diamond grading lab. With AGS certification, you can’t go wrong.

Now that you know more about diamond certification and reliable and trustworthy grading entities let’s look at another grading lab and how it stands compared to other grading labs.

What Is GSI?

Gemological Science International, or GSI, is a recently established organization. GSI has been around for a couple of years only – unlike other labs that are business for decades now.

It’s the only gemological laboratory to be founded in the 21st century. Sadly, they didn’t come to the diamond industry with new ideas or innovative technology and equipment. Instead, GSI built its business by appealing to larger retail chains in the US. 

GSI primarily grades diamonds for big chain stores – and their service is often a fast one. With locations all over the globe, GSI provides gemstone identification on top of grading and appraisal services in the jewelry industry. 

GSI Diamond Grading Report

The GSI report shows the assessment of a gemstone based on the quality and structure of the stone. The measurement and scales are intended to present a reference point when purchasing the stone.

Grading Results And Scales

The 4C’s of a diamond represents its four main factors. Each C is graded on a specific scale to help evaluate the quality and value.


Diamond cut deals with the quality of a stone’s proportions, symmetrical facets, and angles. GSI grades diamond cut grades on the following scale:

  • Ideal
  • Excellent
  • Very good
  • Good
  • Fair
  • Poor


A diamond is assessed for how colorless or white it is. The GSI grades color of a diamond on a scale from D to Z, with D being the most white – and with Z referring to visible yellow or brown tints.

To the naked eye, it’s difficult to distinguish two diamonds of adjacent color grades – and that’s especially true for diamonds that have been graded by the GSI.


The clarity grade determines how “clean” and free from inclusions and blemishes a diamond is. We’d generally recommend buying an eye-clean diamond – so that internal flaws don’t interfere with light reflection.


Carat weight is measured in a standard fashion at GSI and across all diamond grading entities. A GSI report will disclose the diamond’s carat weight though cut quality remains the most critical factor of the 4C’s.


A diamond’s proportions can aid in determining the cut’s quality. However, it’s a challenge for someone that lacks diamond expertise to make an assessment based on the measurements issued in a GSI report.

Additional Grading Information

Other details such as polish and symmetry will also be provided on a GSI certification. While these factors contribute to the overall beauty of a diamond, the 4C’s are far more important.

How GSI Certification Affects The Cost

Since GSI primarily works with prominent chain jewelers, it’s difficult to determine how objective they are in diamond grading. 

While a GSI graded diamond will be less expensive than one that achieves the same grades provided by the GIA, the GSI stone will be worth significantly less.

The looseness and inconsistency in grading make a GSI graded diamond a risky option.


The International Gemological Institute, also known as IGI, is another popular diamond grading entity that has its roots associated with big retailers. 

Similar to GSI, IGI offers faster and less expensive services than other diamond grading labs such as GIA and AGS.

You can expect similar results from IGI and GSI. They’re both known to grade stones at a higher quality so that they can sell for a higher price.

Remember that it’s not in your best interest to go for gems with grades that are “inflated” since it usually means you’ll end up with the same stone – only most likely at a higher price tag.


So, is GSI better than IGI? 

The answer would be no. These diamond grading entities are pretty much the same in terms of their certification methods.

Both of them provide results quickly with a catch of not being consistent and grading diamonds at a higher quality to sell them at a higher price tag.

If you want to have peace of mind when purchasing a diamond, we’d recommend sticking with more reliable diamond grading entities like GIA and AGS.