A Guide to Diamond Certification

Buying a diamond is not an easy thing to do. It takes a lot of consideration to find the right one that could give you the value for your money. Furthermore, purchasing such items could signify a very important moment in your life—be it an engagement, anniversary, or even birthday. Diamonds could mean so much to you and/or your special loved one. That is why it is important to ensure you are paying the diamond’s actual worth. One of the best ways to indicate that is through diamond certifications.

Diamond certifications are provided by independent lab entities to evaluate the diamond. They do this by verifying their grading. However, not all labs are lenient with this and would sometimes give inconsistent and loose grading. To help you with this, below is an information guide to diamond certification:


Let us begin by diving deeper into the definition of diamond certification.

Diamond certifications are the certificates containing a report on a certain diamond. They are issued by a grading entity, which contains descriptions of the various elements found in a diamond. These are color, clarity, length, and width. They are evaluated by trained professionals who scrutinize and measure the diamonds using specialized tools like a loupe or microscope.

However, due to the many lab entities that conduct the diamond evaluation, the grades and descriptions of diamonds evidently vary. And knowing these variations is crucial in understanding and determining the diamond’s value. These lab entities may assign different prices and value to the diamonds. As mentioned earlier, some lab entities are unreliable and not trustworthy. Consequentially, many buyers would get ripped off.

So when buying a diamond, you should be able to receive and review its lab certification. Most importantly, ensure that the diamond you purchase includes a certificate from a highly reputable grading entity. To expand more on what to review in the diamond certification, continue reading below:


Consistency is important when it comes to comparing lab grading entities; even more than the strictness of grading. For instance, when you find that the grade given by an entity seems consistently higher than the grade given by most of the reputable entities, then consider that certificate unreliable. Failing to distinguish this may lead you to buy a diamond with an I color, which you thought was an H.

Understand Subjectivity

One reason why certification gradings are inconsistent is subjectivity. Unbeknownst to most, there is no exact mathematical formula that can identify a diamond’s color or clarity. This is the reason why some labs give a G color rating to another’s H color rating. This could still be acceptable and reasonable on the grounds that they do this consistently.

However, as noted above, you should be wary how not all entities with consistent grading are reliable and trustworthy. A diamond with a weak certificate that is sold at a high price point is usually not worth the value for how much you pay. This brings us to the next:

Price over Certification

By this, we don’t mean to disregard the certificates completely. That would defeat the purpose of this article. What the headline “price over certification” pertains to is being more cautious with the price since it reflects the actual quality, beauty, and cut of the diamond. If you are still unsure whether you are getting what the diamond is worth, then it greatly helps to contact and get advice from an expert.

Diamond Certification Lab Entities

As stated earlier, not all diamond certification are made equal. Likewise, the diamonds are rated differently. Some entities would loosely give a color grading while others on the clarity. On the other hand, you may find other lab certifications that upgrade the grading of the diamond’s elements. While this might seem confusing, we assure you that there is a way out of this dilemma. We are here to help you distinguish which labs are considered by most as trustworthy and consistent. Ultimately, this is to avoid purchasing a diamond that is worth much less than what the certificate claims it to be. Below are some of the diamond certification lab entities you should take note:

GIA Certification

The most well-known diamond grading entity, the GIA or the Gemological Institute of America is by far the most respected and renowned among all other lab entities. Rightly so, as they have been known to give incredible consistency when purchasing any diamond; thus, giving assurance to diamond consumers. GIA has no financial stake in the sale of the diamond and they evaluate the diamonds with these qualities and elements:

  • Diamond’s evaluation date
  • Measurements (in millimeters)
  • Cutting style and diamond shape
  • Carat weight
  • Table %
  • Depth %
  • Culet size
  • Symmetry
  • Proportion diagram
  • Polish grade
  • Girdle thickness
  • Cut grade (Excellent, Very Good, Good, Poor)
  • Color grade (ranging from D to J)
  • Clarity grade (IF, VVS1, VVS2, VS1, VS2, SI1, SI2)
  • Diamond plot showing all blemishes and inclusions
  • Fluorescence grade
  • Laser inscription (if applicable)
  • Security features
  • General comments

Furthermore, GIA is reputable when it comes to their rating of rated Color and Clarity, which is considered as the most rigorous and subjective scales. Because of GIA’s respectable feat, they are the most recommended diamond certifications consumers should watch out for when buying. Sellers who generously provide sellers with GIA certificates are:

  • Brian Gavin Diamonds – known in the industry for their more than 20 years of experience and best cut diamonds.
  • James Allen – with more than 18 years of experience, James Allen is known to give excellent pricing and high regards to their customers’ satisfaction. They also provide the highest tech diamond imagery in the industry.
  • Zoara – more than 50 years of experience under a major diamond manufacturer, this seller boasts an extensive inventory of exceptionally cut diamonds.
  • Blue Nile – even with more than 17 years of experience, Blue Nile is known to offer the largest inventory of diamonds with excellent quality and an array of well-crafted settings.

IGI Certification

IGI which stands for International Gemological Institute is the most popular gem lab in the United States and Canada. They are trusted by major jewelry chains like Kay and Zales. Having to have begun as the blue-collar workhouse of the diamond business, the IGI is usually compared to a factory for the reason that they work fast and their prices are much better than those of GIA—attracting most of the jewelry companies more than the consumers.

However, even with their claim of being a “top-of-the-line” laboratory, the IGI, unfortunately, gives a certification grading that is deemed lax and less consistent than the standard bearers in the industry. For this reason, IGI is usually not a recommended choice when it comes to giving out diamond certificates.

EGL Certification

This next certification is known to give diamonds of inferior quality a much higher price. The EGL or the European Gemological Laboratory, unfortunately, defeats their own claims of having quality diamonds. Many customers who purchase diamonds with an EGL certification are commonly tricked into having found a great deal.

With this, we highly recommend consumers not buy diamonds with EGL certification even if it seems cheaper than GIA certified diamonds. It is known among the most people that any EGL certified stone is more expensive than its identical self in GIA certifications. They grade diamonds higher than other labs. For this reason, the price and value of an EGL diamond is incomparable to those certified by GIA.

GSI Certification

The GSI (Gemological Science International) has only been around for a few years. And unfortunately for this new grading entity, they have let their young age translate to a lack of experience. Nothing in the GSI certification is fresh and innovative. It may be due to how they built their business by wanting to appeal to big retail chains in the United States. They have spent millions of dollars just to score with these major companies. As a result, they significantly undercut their pricing.

Furthermore, the GSI grading is looser than GIA and AGSL; and weaker than IGI and HRD. They also fail to make consistent gradings. For this reason, the same as the EGL, GSI grading is not recommended when buying a diamond.

AGS Certification

Even before the GIA brought in their cut grade, the AGS or the American Gem Society has already offered their own unique cut grade scale, which ranges from 0 to 9, with 0 being the “ideal”. The AGL is known to have been the original lab that provides diamond cut grades. Back in the day, no diamonds are called “ideal” if they do not bear an AGS certificate. However, with the entrance of the GIA’s cut grade, their share in the market has significantly dropped.

In an attempt to redeem itself from the loss to GIA, AGS tries to bill itself as being fancier and more refined than GIA. Unfortunately, even with this, many people claim that there is hardly anything to distinguish between the two; save for the fact that AGS grades slightly looser than the GIA. For this reason, many large companies would capitalize this fact and take those diamonds that don’t receive the intended grade with GIA to AGS in hopes that they would receive an upgraded version of their previous grade.

However, there isn’t much of a market-wide consensus to this fact, so diamonds with AGS certification still sell at similar prices to their GIA equivalents. Overall, the AGS is still a very reliable laboratory and is definitely placed at the same level as GIA when it comes to recommended certificates.

HRD Certifications

This diamond grading certification is an organization based in Europe. The HRD or the Hoge Raad voor Diamant is usually not regarded as a legitimate certification alternative in the United States. Even with that, they still claim to be the authority for diamond grading in the world.

However, in contrast with their claim, HRD has been giving an incredible inconsistency with their grading; usually averaging about two Color and/or Clarity grades above GIA. Also, they price much higher with their diamond equivalents to GIA. So it is safe to say that, like those inconsistent diamond grading certificates, HRD is not recommended.


When looking to buy a diamond, you should consider the diamond certificate; most especially those that produce consistent, reliable, and trustworthy grading. And those diamond certificates that are highly recommended are from the GIA and AGS.

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Kevin Lee is a former tech advisor who cut his teeth in Silicon Valley. He now spends his time sharing his passion for investing in diamonds and jewelry. You can reach Kevin for any comments by using this form.