GSI Certification Guide for Diamond Buyers

Last Updated on October 30, 2025 by Learning Jewelry

Wondering about GSI diamond certification?

You’re in the right place.

In this Learning Guide, we’ll go over the Gem Science International laboratory and answer questions like:

GSI certification - featured image

What kind of diamond grading reports does the GSI offer?
Are GSI diamond certificate a good certificate?
What is on a GSI report?

What is GSI Certification?

The Gemological Science International is a grading authority for loose diamonds and engagement rings.

There are a decent amount of grading authorities around the world for diamonds. Only a handful of them are very popular. Out of the biggest grading labs in the diamond industry, GSI is the only one that was established in the 21st century.

The GSI grading lab is popular in big name brick and mortar retailers. Places like Kay, Jared, and Zales get big discounts for buying GSI certified diamonds.

Not only does the GSI give them great prices for buying in bulk, they have a quick process.

It doesn’t take a genius to know that good things can’t be rushed, even if you have the skill. The same goes for diamonds with a GSI certificate.

What is on a GSI Grading Report?

There are three types of grading reports you can obtain from the Gemological Science International. They may offer printed or PDF files for their reports.

Natural Diamond Report

I have a printed natural diamond report. At the top, it says GSI report of Authenticity.

It shows you the shape/cut grade (if applicable), clarity grade, diamond color grade, and carat weight of my diamond. It tells you other diamond details like polish, symmetry, and measurements.

If the ring setting has other small diamonds in it, it’ll summarize the details of those stones. It will say the approximate carat weight and number of stones. Additionally, it’ll say the carat metal of the setting if it’s a ring.

GSI inscribes the girdle of your diamond with the report number, which is a great security feature.

On the GSI report website, they show more details on their sample report. My GSI report didn’t come with anything other than what you see above and the GemEx report.

Lab Grown Diamond Report

A lab grown diamond report from the GSI has all the same information as the first picture in the natural diamond report. It’s inscribed with LAB GROWN GSI + its report number on the girdle of the diamond.

You get an additional document that shows a clarity plot, enlarged photograph, color scale, clarity scale, and the same specifics as the second sheet in the natural reports.

Colored Stone Report

The last type of report you can get from the GSI lab is the Full Gemstone Examination colored stone report. Colored stones refer to any colored gemstone. However, most certified colored gemstones are faceted gemstones.

This report will include a photograph of your gemstone, the gemstone identification, weight, color, shape, and other information of the stone.

There’s a few different colored stone reports that may have additional analyzation. They are the IGX report, SGX report, and the MGX report.

Some grading labs have different diamond reports for the same type of diamond. The GIA does the same with their reports, such as the Diamond Dossier reports.

Should I Get a GSI Report for My Diamond?

Alongside many other jewelry research sites, I don’t recommend buying diamonds or engagement rings with GSI diamond certification.

GSI reports are catered to mall retail stores, so you won’t see them as much online. They are out there though.

These reports weren’t designed with the customer in mind. GSI works for the diamond vendors.

I have a GSI report for my Tolkowsky engagement ring I bought before I left Kay. At the time, I believed I bought the best brand in the store. I didn’t know anything about a diamond certificate, and NOBODY TAUGHT ME.

My GSI diamond came with a GemEx report, which is not a grading report. It analyzes the brilliance of your diamond’s fire, sparkle, and scintillation. That’s not essential to buying a diamond, but a cool added thing to know about the white light and rainbow light in your diamond.

They don’t like to talk about diamond grading reports because very few of their inventory have one.

The main issue with a GSI certified diamond is the quality control and consistency. There are stories of people buying a GSI diamond and sending that particular diamond to another grading authority.

Much to their disappointment, the GSI diamond was graded below what the certificate said.

FAQ

Here are some of the most popular questions asked about the GSI and diamond certification.

Why is Diamond Certification Important?

In my personal opinion, you should only buy certified diamonds. A certified diamond ensures that you are getting what you paid for.

Whether you did all your diamond research on the 4Cs or not, you want to know you’re not being ripped off.

Majority of diamond engagement rings at stores like Kays, Zales, and Jared have uncertified diamonds. That’s because their inventory consists of mass produced merchandise.

Read also: Kay vs Zales

An engagement ring at Kay’s comes in a big jewelry bag from the home office. There’s a range of clarity grades on these. The didn’t used to list it on the tag, but started back when I was still working there years ago.

Would you be mad if you paid for a ring with supposed diamond grades, only to find out the grades are lower than you paid for?

Most people would be upset. That’s why diamond certification is there. The problem is, not every grading authority is the same.

Read also: Grading Labs to Avoid

What is the Best Diamond Certification?

So if you shouldn’t buy a GSI diamond grading report, which grading certificate should you buy?

If you’ve read any of my other guides, you’ll probably know that we only recommend buying GIA certificates or AGS certificates. The Gemological Institute of America and the American Gem Society are considered the top in the jewelry industry. Here’s why I recommend a GIA vs a GSI report.

However, it should be noted that AGS certificates are less common than GIA certificates. Their diamond cut grade standards are a little different than GIA certification.

If you’re buying lab grown diamonds, they’re are other recommended labs.

Where Can I Buy a Reliable Diamond Grading Certificate?

There are many places that sell GIA certified diamonds both local and online. However, I suggest you skip the big retailer stores. Check with a local jeweler or family owned jewelry store if you’re trying to keep local.

I recommend going online for GIA certified diamonds. You can compare hundreds of diamonds through 360˚ viewing and other features. You don’t get to compare that many diamonds in any local store.

They’re also much cheaper online. My favorite places to buy GIA certified diamonds is James Allen. Even though they’re the same company as the overpriced big name stores, the selling model is much better.