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You may already have some experience buying diamonds and know what to look for; high clarity, good quality cut, a highly-graded color. But what about diamond certification?

Diamond certification is an incredibly important part of any diamond purchase, but it’s often forgotten about, especially by those new to the diamond world. Now, there are many types of diamond certification out there. Potentially the most well-known is from the GIA, who set the standard for diamond certification practices.

However, today I’ll be exploring the GSI, a relatively new diamond certification provider. Here’s your introductory guide GSI diamond certification:

  • Who Are The GSI?
  • What Are The Advantages of GSI Diamond Certification?
  • What’s Included in a GSI Grading Report?
  • My Final Recommendation

Who Are The GSI?

Gemological Science International (GSI) is a relatively new for-profit diamond certification laboratory, in contrast to many well-known names who have been around for decades (such as the GIA). They were created to directly appeal to big retail chains, and service big names such as Kay and Zales.

If you want to ensure that you are getting high-quality diamonds, it is best to shop at retailers that only stock diamonds from internationally recognized labs such as GIA and AGS. My top recommendations for these types of retailers are Whiteflash, followed by James Allen, and Brilliant Earth.

Even though they have only been around for a few years, they’ve developed a foothold all over the globe. They provide diamond certification, alongside grading and appraisal services for those looking for an appraisal on fine jewelry.


What Are The Advantages of GSI Grading?

My issue with GSI is that of objectivity. Because they predominantly work with large retail chains, ascertaining how objective they are when it comes to diamond certification is difficult. So are there any advantages? Here’s what I think:


  • Diamond vendors experience a very fast turnaround.
  • Due to their work with retail chains and bulk products, their work will usually be offered with discounts.


Unfortunately, with advantages come disadvantages. In general, the GSI is seen as having a much ‘looser’ approach to certification, meaning diamonds might get better grades than they actually deserve. On top of this:


  • Diamonds certified by the GSI will more likely be less valuable than diamonds certified by more respected names.
  • The GSI cannot guarantee consistency within their grading.
  • Due to inconsistency in grading, it’s practically impossible to compare two diamonds.

What’s Included in a GSI Grading Report?

The all-important grading report is the evaluation given to every diamond, where modern gemological techniques are used to appraise the structure, dimensions, and quality of a diamond. They provide the background and data on a diamond that can be explored upon purchase.

So what does this report include?


  • Cut: This refers to the quality of the diamond’s cut itself, which can range from Ideal to Poor.
  • Clarity: This refers to the purity of the diamond, and whether it has any internal blemishes that can affect the overall light performance of the diamond.
  • Color: It might seem odd, but diamonds can actually come in different colors. The most popular (and typically most expensive) are colorless, but some can contain hues of yellow or even brown, which are evidently less popular.
  • Carat: This is another term for weight, and is the actual size of the diamond in question. For example, 2 carats is roughly 400 milligrams.


These are also known as the Four Cs, and you can find out more about these here.


Alongside the grading report, the GSI also provides:


  • A Trade Consultation Report;
  • A Hearts and Arrows Report;
  • A Light Performance PSX Report;
  • Laser inscription;
  • Metal engraving.


In comparison to other, better-known laboratory grading reports, the GSI really doesn’t compare. They are too inconsistent in their approach to grading, and whatever value you may find in a GSI diamond is immediately eroded by a lack of trust offered by the certification.


You may think that the GSI must be trustworthy because they’re used by big retail names such as Kay or Zales. However, remember that the profit motive of a big retail chain will make them utilize a low-quality service to save on their overheads, allowing them to quickly sell new product for more than it is actually worth.

My Final Recommendation

I don’t recommend purchasing a diamond with GSI certification. It’s a much looser certification, especially when in comparison with the GIA’s certification, and even the IGI.


A diamond with GSI certification will not provide you with the peace of mind, or even the factual data, you need when trying to ensure that you’ve got your money’s worth. However, GSI certification does offer one benefit. If you find a diamond retailer selling GSI-certified diamonds, they’re probably not worth buying from.

I would suggest purchasing diamonds from retailers that only stock diamonds from internationally recognized labs (GIA, AGS et al), my top recommendation would be Whiteflash, followed by James Allen, and Brilliant Earth.

Discover More About Diamond Certification

Diamond certification is where gemstones have been graded by a reputable gem lab on the basis of their Four C attributes, which are Cut, Carat, Color, and Clarity. These diamonds have undergone quality analysis by a trusted gemological lab, such as GIA or AGS, and have been issued a lab report, which is commonly referred to as a “certificate” or “report”.


Purchasing a diamond with the right certification is a vital step in making the most of your money and walking away with a good quality diamond that will both stay good quality and retain its value over time.


If you’re looking for more information on diamond certification and the type you should look for, head to my diamond certification page.