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Diamond Grading Lab: Which Diamond Certification Is Best?

Diamond Grading Lab: Which Diamond Certification Is Best?

When shopping for diamonds, you have probably stumbled upon the term diamond certification. Independent diamond grading labs assess diamonds and provide these certificates, verifying a diamond’s grading. 

So, the question is: Which diamond certificate is best?

Among several diamond grading entities, two stand out as most reliable and trustworthy: GIA and AGS.

But what is diamond certification, anyway? How does it work? In this article, we’ve covered everything you need to know about diamond certification – so be sure to keep scrolling!

What Is Diamond Certification?

A diamond certification or grading report is a document you should receive upon purchasing a diamond. This certification is issued by an objective third-party certification entity and describes a stone in detail.

Each entity evaluates and grades diamonds differently, and sometimes, this difference can be pretty significant. There are quite a few diamond grading labs; you should know which ones are reliable and trustworthy. 

It’s worth noting that, since diamond grading reports aren’t created equally, diamonds’ value and price aren’t comparable across varying reports. 

So, make sure that you buy a diamond with a grading report from a highly reputable grading lab. And, while we’re at it, don’t forget to review the stone closely before you make a purchase.

Related Read: What Is The Difference Between Certified And Non-certified Diamonds?

A Review Of Each Diamond Grading Lab

In short, we highly recommend sticking with GIA certifications; it’s the most reputable diamond lab out there. Other labs you can take into consideration are AGS, GCAL, and HRD, but IGI is still improving its diamond grading process.

Unfortunately, EGLS has lost so much of its market share and credibility. As for GSI, it’s a good choice – but can sometimes have inconsistency issues.

With that brief intro aside, let’s discuss each of these labs and their certification in more detail. 

GIA Certification

The Gemological Institute of America – or GIA for short – is a non-profit organization devoted to researching gemstones and jewelry and the education of people in this industry. 

GIA studies, analyzes, and grades all sorts of gems. In addition to their lab services, GIA trains gemologists and offers in-depth research and education support for the diamond industry. 

Currently, GIA’s diamond grading reports are top-rated certification and verification documents in the diamond industry.

GIA offers two types of certification – complete reports and diamond dossiers for tiny diamonds. As one would expect, the dossiers are less expensive as opposed to the full diamond reports and don’t include clarity plots that show locations of inclusions.

Since the locations of inclusions aren’t assessed in dossier reports, GIA requires a mandatory laser inscription of the stone. However, this isn’t the case with complete diamond reports. 

As an independent diamond grading lab, GIA has no stake in diamond sales. They assess each gemstone based on various factors, including:

On the other hand, it’s commonly discussed how GIA determines excellent cuts. One problem with their grading system is their broad criteria when giving excellent cut grades to diamonds – “excellent cut grade” being the highest cut grade on GIA’s scale.

It has been suggested that since AGS uses a proportion-based method when assigning ideal cut grades in their diamond reports, its grading system is superior to that of GIA.

Nevertheless, GIA is the strictest diamond grading entity, the most renowned and reputable one out there. So, if you’re shopping for diamonds, we’d recommend getting a precious stone that’s accompanied by the GIA certification.

AGS Certification

The American Gem Society, AGS for short, is a membership organization for suppliers, traders, appraisers, and jewelers. The company has been operating since 1934, but the AGS labs were founded in 1996.

AGS also has an advanced equipment division founded in 2004. AGSL (American Gem Society Laboratories) is the division that assesses diamonds and has developed its grading standards. 

One would say it’s the biggest competitor to the GIA and is also a reputable grading entity in the diamond industry.

However, AGSL isn’t as strict as GIA when it comes to diamond clarity grading. 

According to our research, diamonds in the SI2 clarity range graded by the AGS don’t have SI2 clarity grade according to the GIA. So, there’s a bit of inconsistency with the AGS certificate.

Still, AGS provides one of the best diamond reports – and you wouldn’t make a mistake if you went for a diamond with their certificate.

HRD Certification

Founded in 1973, HRD Antwerp is owned by the Antwerp World Diamond Center, representing the Belgian diamond industry. By the way, Antwerp is one of the leading diamond trading and supply centers.

The HRD lab’s standards are somewhat similar to the ones utilized by the GIA. Even more so, HRD follows grading methods set by the International Diamond Council and is also reliable to some extent.

You see, when it comes to grading diamond clarity and color, HRD can be a bit inconsistent, so please consider this if you opt for a diamond with HRD certification.

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

IGI Certification

International Gemological Institute, also known as IGI for short, was established in 1975 with its headquarters in Antwerp. 

IGI has several branches across the globe and is one of the biggest diamond grading labs in the world. On top of that, IGI has its own gemology school.

While IGI is extremely large, their labs in different countries use slightly different criteria when grading diamonds.

We could rate IGI as less strict than GIA, and you can expect grade inconsistency when buying IGI graded diamonds.

However, there are no two identical diamonds. So, applying a generalized approach isn’t a good idea when buying diamonds since each case is different and should be treated differently.

At the end of the day, though, you can expect some grade inconsistency in the overall grading methods when it comes to IGI certification.

Related Read: Is IGI As Good As GIA?

GSI Certification

Gemological Science International – GSI for short – primarily grade diamonds for large chain retailers in mass numbers. Recently, GSI has expanded its services to a number of countries worldwide.

GSI is generally a favorite choice for big stores since they grade diamonds faster than GIA and AGS. It’s pretty close to IGI in diamond grading, and they often grade diamonds one grade lower than GIA or AGS.

Again, as we already stated, since each diamond has its unique characteristics, it’s crucial that diamonds are considered and evaluated individually.

With that being said, we recommend caution when evaluating GSI certified diamonds. You can expect a certain degree of grade inconsistency; be sure you ask a professional for additional opinions.

Related Read: Is GSI Better Than IGI?

EGL Certification

The European Gemological Laboratory, also known as EGL, used to have significant shares in the diamond industry – but it has lost much of that credibility. 

EGL is reorganizing itself, and, at least for the time being, we don’t recommend relying solely on their diamond grading reports. 

As a result of their reputation, even RapNet doesn’t allow diamonds with EGL certification to be listed on its platform.

As you would expect, we strongly advise avoiding diamonds with EGL certification since they’re highly inconsistent with their grading.

How Are Diamonds Certified?

It’s crucial to understand how diamonds are graded in the first place to make a well-informed decision on the various diamond certifications.

The major grading entities all have remarkably similar methods for analyzing and grading diamonds. 

The process typically involves a couple of graduate gemologists independently evaluating the cut, carat, color, and clarity of stones. The final grades are drawn out after all the factors have been assessed.

This process helps to reduce potential errors in the determination of a gemstone’s final grade, although it doesn’t eliminate it entirely.

Some diamond grading labs are known to have inconsistencies in diamond grading processes, as mentioned earlier. This inconsistency in diamond grading is more noticeable when a stricter diamond grading lab reevaluates a stone.

Interestingly enough, diamonds aren’t certified. You see, no lab would state that it’s certifying diamonds as it could cause them some legal troubles. 

So, all labs confirm is that they have evaluated and graded a particular diamond based on their best opinion as represented in the certification.

Consistency Is The Key

Part of the reason behind the dominance of the GIA and AGS is their consistency. They’re both able to consistently grade stones accurately. 

So, for example, if you were to send a diamond to either GIA or AGS for assessment, you’d most likely receive identical grading results without any significant discrepancies.

It’s worth noting that a slight difference is acceptable within the industry.

The Lab’s Organizational Structure Matters

Being a non-profit organization, GIA is known to be more objective than other labs when it comes to grading diamonds.

Other diamond grading labs are heavily influenced by profit motives and are generally more customer-oriented. As a result, the imbalance in grading results is an open secret within the diamond industry.

Sometimes, commercial diamond grading labs would give stones one grade higher on average than that provided by the GIA in order to satisfy their customers.

If you find a diamond with similar grades from different labs but with a lower price than the one issued by the GIA, don’t be misled. The diamond might be of lower quality.

Generally, the diamond grading report is crucial when shopping for diamonds from a buyer’s perspective. While there are many different diamond grading labs operating worldwide, your best and safest bet is to purchase a stone that the GIA or AGS grades.

Learn More: How Do I Get My Rough Diamond Certified?

Deeper Dive Into GIA And AGS Grading Methods

Okay, now it’s time to look a the GIA and AGS grading methods a bit closer. 

GIA Diamond Cut Grading System

The most crucial innovative system in the diamond industry is, without a doubt, GIA’s diamond cut grading system. It was introduced to serve as the standard for all diamonds and gemstones to be specifically graded.

Even though the 4C’s were already well known and several other grading methods were used, it became necessary to have a uniform diamond grading system to promote consistency across the diamond industry.

Today, GIA’s 4C diamond grading system is the most commonly used and accepted grading diamond grading standard.

The key factors of a diamond that the system takes into consideration when assigning grades are color, clarity, cut, polish, and finish. Depending on its quality, a diamond can receive one of five grades after being evaluated by the GIA:

  • Excellent Grade
  • Very Good Grade
  • Good Grade
  • Fair Grade
  • Poor Grade

Besides the features mentioned above, GIA evaluates brilliance, scintillation, length-to-width ratio, and symmetry.

AGS Proportion-Based Cut Grade System

The AGS proportion-based cut grading system is a major contender to GIA’s grading system for dominance as the diamond industry’s standard grading system.

Interestingly enough, both AGS and GIA were founded by Robert Shipley

However, due to disagreements over specific parameters and methodology used in diamond grading, both organizations drifted apart, leading AGS to establish its separate laboratory and grading system.

As opposed to the GIA’s grading system, which provides an overall designation based on taking into consideration all of the stone’s features, AGS’s proportion-based grading system takes into consideration cut, color, and clarity. 

It assigns each diamond’s factor one of 11 levels. These levels range from 0 to 10, “0” being the best grade and “10” being the worst. 

If a diamond receives three 0s, that means it has been cut perfectly, has perfect proportion and symmetry, and carries a flawless polish. These precious stones must also have the perfect light performance.

Bottom Line

So, which diamond certification is best?

While there are several diamond grading entities, each using its own grading system, the most reliable and trustworthy ones are the Gemological Insitute of America (GIA) and the American Gem Society (AGS). 

So, next time you go shopping for diamonds, be sure to get a stone that’s accompanied by the GIA or AGS certification. 

Also, don’t forget to examine the stone yourself before you make the purchase – and don’t be afraid to ask professional gemologists for help if you have any concerns.

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