GSI vs GIA: Which Diamond Certification Should You Trust?

Last Updated on October 18, 2023 by Juli "Jewels" Church

Wondering about the difference between a GSI and a GIA diamond certification? 

You're in the right place. In this Learning Guide, we'll get to the bottom of why it's good to have a certification for your gemstone and as well as answer other burning questions about these two diamond grading authorities. 

  • Why are GSI diamonds hard to find online?
  • Are GIA diamonds expensive or cheap?
  • Is a GIA certified diamond really worth it?

Main Differences Between a GSI vs a GIA Certification:

  • A GSI certificate was created for chain retailers, whereas GIA certificates were created for everyone.
  • GSI diamond certifications have been around since 2005, whereas GIA diamond certifications have been around since 1940.
  • You're likely to run across a GSI certified diamond at a local chain retailer, whereas more GIA certified diamonds are found shopping online.
  • The GIA is the world's leading resource in diamond and gemstones, whereas the GSI grading laboratory holds no significance to the industry.

GSI Diamond Certification vs GIA Diamond Certification: Which Came First?

GSI Certification

The Gemological Science International (GSI) is a gemological laboratory used for grading diamonds. They also grade colored gemstones. The GSI lab is one of the newest diamond certifications in the diamond industry, having formed in 2005. GSI reports are the only widely recognized lab formed in the 21st century.

The home office of the GSI grading lab is in New York City. Other branches of the lab exist around the world, totaling in about 13 different locations. Some of these countries include:

  • India
  • Dubai
  • Israel
  • Belgium
  • Hong Kong
  • Botswana

Instead of using a team of diamond graders like other gemological labs , the GSI laboratories assess their diamond grading by using software in addition to gemologists. They pride themselves on always looking for the latest innovations and efficiency in grading diamonds. They are one of the largest independent grading laboratories today.

GIA Certification

The Gemological Institute of America (GIA) created the 4cs, the grading system in which all diamonds are measured. Not only are they the leading authority in certifying diamonds, they are also the leading authority in diamond and gemstone research and discovery.

The GIA was founded in 1931, but the 4cs grading scale wasn't created until 1941. This is after Marcel Tolkowsky learned how to create ideal cut diamonds, or diamonds withs exact proportions and optimal brilliance.

After the 4cs grading system was implemented, some diamonds graded came with certifications, also known as grading reports. The GIA is based in America, but has gemological laboratories all over the world in places like:

  • Taiwan
  • China
  • United Kingdom
  • India
  • Japan

A GIA diamond report is generally classified by most jewelry experts as the best diamond certification authority available in the industry. It makes sense. They're the leading authority. However, other competing grading labs believe theirs is better.

GSI Versus GIA Reports

Both the GSI diamond certification and GIA diamond certification give reports with their diamonds, colored stones, or fancy colored diamonds. Let's compare the similarities between the two grading authorities.

GSI Report

The GSI offers reports for natural diamonds, lab grown diamonds, and colored gemstones. They offer reports for each category in different formats.

The Comprehensive Diamond Examination Report is the most comprehensive of all of them. This diamond certificate may tell you:

  • Diamond Shape
  • Carat Weight
  • Color Grade
  • Clarity Grade
  • Cut grade
  • Fluorescence
  • Polish/Symmetry
  • Measurements
  • Plotting diagram that shows
GSI report CDX

The Intermediate Diamond Examination Report has the same diamond details as the FDX Report, but in a compact form.

The Special Diamond Examination Report includes:

  • Carat Weight
  • Diamond Shape
  • Color Grade
  • Clarity Grade
  • Measurements 
  • Photo of a gemstone and/or jewelry piece
GSI Grading Report

The Modified diamond examination report contains concise information about the diamond including:

  • Carat weight
  • Shape
  • Color
  • Clarity
  • Measurements
  • Brief description about the piece
GSI report MDX

GIA Report

Like GSI certified diamonds, GIA diamonds can have multiple variations diamond certificates. They offer a grading report for mined and lab diamonds, colored gemstones, and fancy colored diamonds (mined and lab-created). They also offer reports for pearl jewelry.

The standard diamond grading report is the GIA Diamond Grading Report. It is only used for a natural loose diamond graded at .15 carats or more. This report includes:

  • Diamond Cut Grade
  • Diamond Color Grade
  • Diamond Clarity Grade
  • Diamond Weight
  • Graphic of Diamond Proportions
  • Plotted Diagram

The Natural Diamond Origin Reports includes the same as the GIA DGR in addition to:

  • Confirmation of Geographical Origin
  • Laser Inscription of Report Number

The GIA Diamond Dossier Report includes all the same information as the GIA DGR, but also includes laser inscription. You can request inscription on an engagement ring center stone with a standard GIA diamond report.

GSI Diamond Certifications vs GIA Diamond Certifications

You know the information that both of these diamond grading authorities offer on their grading reports. Now lets see how the measure up from pros and cons standpoint.

GIA Reports 


  • Considered the best in the diamond industry
  • GIA certifications are better for resale or trade-up
  • Offers diamond origin


  • GIA graded diamonds are more expensive
  • Harder to find at chain retailers like Kay or Zales

GSI Reports 


  • GSI certified diamonds are more affordable
  • Easier to find at chain retailers like Kay or Zales


  • Harder to resell
  • Looser diamond grading standards


If you're stuck between choosing a GSI grading report or a GIA grading report, here's my expert opinion.

When shopping for a diamond or engagement ring online, I'll always recommend a GIA report over any other. GSI reports are great too, but they're less common online. James Allen is one of our favorite for GIA grade diamonds of natural origin. For lab grown, we recommend Brilliant Earth's GIA certified diamonds. GIA lab diamonds are a lot harder to find, so we also recommend IGI or GCAL certificates for those.

You're less likely to come across GSI reports online, but some retailers offer those as well for their lab diamond jewelry. However, I advise you to steer clear of these in general. There are much better grading authorities.

Here's why:

You'll be more likely to run into GSI reports at chain retailers because that is why they were created in the first place. If you'll recall, I mentioned that GSI reports use grading software for their grading scale. This allows them to produce more graded diamonds at a faster rate. They also sell them to retailers in bulk pricing. Not only that, but they will customize the diamond report to fit a retailers look.

The bottom line is that GSI laboratories and their grading reports were created with the diamond retailer in mind, not the individual buyer. The retailer will then hike up the price in order to make a profit.

In saying that, I still don't recommend purchasing a GIA certified diamond from a place like Kay or Zales. Even their GIA certified diamonds go for much more than ones found online of the same grade. James Allen is also under the same umbrella company, but they don't price the diamonds the same way.

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