A Full Guide to AGS Certification: Is It a Smart Investment?

AGS diamond grading: Yes or no?

Many shoppers seek GIA certification when shopping for a new diamond. But, what about AGS certification?

You may see the AGS acronym during your search, and that’s no reason to shy away from a diamond. AGS criteria slightly differ from GIA requirements, but which grade is the better option?🤔 It’s really a matter of preference, so let’s go over the ins and outs of AGS diamond certification so you can make an educated decision regarding the perfect diamond.

A Full AGS Diamond Certification Diamond Report Guide

A brief history of the American Gem Society (AGS)

Started in 1934, the American Gem Society (AGS) has a rich history that dates back almost as far as the GIA itself! Founded by the same man, Robert Shipley, the AGS is a kind of trade association that serves an important cause: uniting retail jewelers around a code of ethics that protects buyers from fraud and false advertising.

The AGS protects consumer interests and encourages a transparent buying process, and it has over 3,400 members today! Their members consist of retail jewelers, gemologists, and diamond professionals from all areas of the business that strive to foster discussions around jewelry ethics and morals.👍🏻

In 1996, the AGS opened the American Gem Society Laboratories (AGSL) to provide their own thorough diamond grading and inspection. They also created an advanced instruments department in 2004, working toward using only the latest technology in diamond analysis.

The reason for the AGS’ departure and lab formation was actually a disagreement between the AGS and GIA: the AGS wanted to include crown and pavilion angle measurements as part of a diamond’s cut grade, while the GIA did not. By choosing to form their own lab and add these measurements, the AGS revolutionized how cut quality is assessed in diamonds.

The AGS is still rather small when compared to the diamond giant that is the GIA, but their cutting-edge techniques for grading diamond cut and analyzing light performance are some of the best in the world.🏆 Next, we’ll look at how the AGS puts these procedures to the test to grade diamonds.

How does the AGS grade diamonds?

The AGS grading lab uses a strict scale to measure diamond cut and light performance, and they also measure color, clarity, and carat with great accuracy. Let’s look at how exactly the AGS grades diamonds that enter their lab for inspection.

Diamond Cut

The AGS emphasizes cut quality when grading a diamond, and their scale demonstrates how serious they are about precision. The GIA uses a 5-word scale that ranges from Excellent to Poor, but this isn’t quite enough for the AGS.

Instead, their lab uses a numerical scale ranging from 0 to 10 to grade diamond cut. These numbers are then classified by a verbal descriptor to break down what each grade means. For example, a 0 grade is considered an Ideal cut, whereas a grade of 8 to 10 denotes a Poor cut.

You can see how the two grading scales differ below:

IdealExcellentVery GoodGoodFairPoor
ExcellentVery GoodGoodFairPoor

Because the AGS scale is proportions based, many regard it as the superior, more accurate representation of diamond cut quality. The scale takes into account all appropriate angles and facets that impact a diamond’s sparkle, covering their bases with more precise grades.

However, the GIA argues their scale accounts for varying proportions, which can be combined to produce identical fire, brilliance, and scintillation. Either way, there’s no denying that the AGS provides a more in-depth grading scale and a closer look at all of the features that can impact a diamond’s cut.

Focus on light performance

As we’ve mentioned before, the AGS places a heavy emphasis on light performance when compared to GIA labs. AGS grading labs utilize Angular Spectrum Evaluation Tools (ASET) to explore a diamond’s light play and gain a better understanding of each stone’s potential light leakage.

By using ASET imagery, the AGS can perform deeper cut quality assessments that take into account not just IF a diamond sparkles but also HOW WELL it actually does. Plus, you can find these ASET images on the AGS diamond report for each gem, meaning you as the buyer can also get a firsthand look at each diamond’s performance!🌟

GIA Excellent vs. AGS Excellent-1 and Ideal-0

Does the GIA’s Excellent cut grade measure up to the AGS’s Excellent and Ideal cuts? These grades are at the top of their respective scales, but they do have some differences in measurements that make them a bit different.

Both labs use Sarine technology to measure their diamonds, but they each have their own version of the software that suits their grading needs. They also measure diamonds from opposing viewpoints, meaning the resulting numbers are different as well. For example, one lab may measure a diamond from its girdle edge from the midpoint of the valley, whereas the other lab may account for peaks, valleys, and other discrepancies within its measurements.

The GIA also rounds their data to the nearest half percent while the AGS does not. In fact, the AGS records measurements as collected, so their numbers are more precise in comparison. While this may not seem like a big deal, even a tenth of a percent can mean the difference between Ideal and Excellent cuts on the AGS scale, meaning the GIA scale provides more leeway for less exquisite diamonds.

Furthermore, the AGS focuses much more on light performance than the GIA, and this analysis is part of the final cut grade. With ASET imagery and 360° evaluations that assess a diamond’s optical precision, the AGS can prove whether a diamond receives an even distribution of light throughout the gemstone.🔍 The measurements captured by both labs are crucial to cut quality, but this extra emphasis on light performance pushes AGS Ideal and Excellent diamonds above the rest.

Finally, the AGS provides cut grades for fancy shapes, whereas the GIA only grades round brilliant stones. Given the current popularity of fancy-shaped diamonds, this gives the AGS a serious edge over the GIA for unique diamond silhouettes!😘

In short, both the GIA and AGS labs carefully measure the facets, angles, and proportions of diamonds to determine their cut quality, but the AGS just takes things a few steps further to set their highest grades apart from other diamonds.

Diamond Color

The AGS labs use a color grading scale similar to the GIA, using master stones graded by GIA labs to compare the diamonds they are grading within established color parameters. These diamonds are graded face down in a properly lit environment and on a white tray to simulate a standard backdrop for all diamond color grading.

The color scale implemented by the AGS is also numerical, with grades ranging from 0 to 10.  Half sizes are included in this scale, and these numbers correspond to a range of hues from Colorless (0-1) to Light (7.5-10). The numerical scale allows the AGS to assign a fairly precise grade to each diamond, although all assigned grades are allowed a one-grade deviation.

Diamond Clarity

Just like their scale for cut and color, the AGS utilizes a numerical 0 to 10 scale for clarity as well. This scale is most like the GIA equivalent, with 0 equating to a Flawless or Internally Flawless stone and 10 resembling an I3 (Included) diamond. However, you should still always inspect each diamond yourself to ensure it’s free of visible blemishes and inclusions.

Diamond Carat

The AGS uses the standard weight model to gauge diamond carat. Diamonds used as center stones usually start at .25 carats and increase from there, with some gems reaching a staggering 10, 15, or more carats!

One carat is equal to 200 milligrams, and carat weight is typically expressed in full or half sizes (0.5, 1.0, etc.), although quarter sizes are often available as well.

What types of grading reports does the AGS offer?

The AGS provides more than one kind of diamond grading report, and each serves a different purpose. AGS certification can be broken down into three documents:

Diamond Quality Report

The diamond quality report is the standard documentation provided by the AGS for a graded diamond. During the grading process, labs utilize their advanced tools to produce a report that is proportion-based for the most accurate cut grade possible.

In this AGS diamond report, you can find information regarding a diamond’s 4Cs with relevant grading scales so you can understand how each grade compares to the overall ranks. Additionally, you can find further data regarding the stone’s proportions and finish details as well as a diamond plot with inclusions and relevant measurements.

Platinum Diamond Quality Report

AGS Platinum Diamond Quality Report Sample
Image: AGS

The platinum diamond quality report is a comprehensive document that includes all of the information you would find in the standard diamond quality report. However, it also includes crucial information about light performance for a deeper understanding of a diamond’s fire, brilliance, and scintillation.

In addition to 4Cs grades and relevant proportions, the platinum report provides ASET images of the diamond. ASET images use a color-coded diamond plot to indicate light return and leakage, providing further information about sparkle as well as the quality of the stone’s cut. Because cut is directly related to sparkle, seeing the balance of red, blue, and green light on ASET images can help you pinpoint problematic areas with poor light play.

Proprietary Light Performance Diamond Quality Report

The proprietary light performance diamond quality report is essentially the same as the platinum report, but it’s a branded document that’s ideal for a retailer that’s developed their own proprietary diamond cut.

The report boasts the same details regarding the 4Cs and proportions as well as ASET images, but the document has the company’s logo prominently displayed at the top. The report is also customizable, so a retailer can select how they want to present the data regarding their new diamond cut. Having this documentation to back up their cut provides security and respectability to their product and protects shoppers from buying bad diamonds.🙌🏻

Whiteflash A CUT ABOVE diamonds

One major example of this proprietary report is the one created for Whiteflash. Their A CUT ABOVE diamonds feature a cut of their own design, and they’re backed by an AGS proprietary light performance report.

Sample of Whiteflash’s A CUT ABOVE Proprietary Light Performance Diamond Report
Image: Whiteflash

Whiteflash customizes their reports to feature multiple ASET images in addition to the standard 4Cs and proportions information to further inform shoppers of a diamond’s light performance as it’s inspected face up and face down. The report also proudly displays the “A CUT ABOVE” logo right above all relevant grading information for refined, personalized touch.

AGS vs. GIA certification: Which is better?

So if the AGS and GIA both provide excellent reports, which one should you choose when shopping for a diamond? Honestly, both are top-tier organizations that provide high-quality grading and documentation for diamonds.⚖️

The GIA is definitely the titan among diamond grading laboratories, and they offer more precise grades when it comes to color and clarity. However, although the AGS is much smaller, their highly accurate cut grades give deeper insights into a diamond’s cut quality and light performance. This proportion-based cut grading technique is more straightforward and can easily help high-quality diamonds stand out among the crowd.

If you’re looking for a fancy cut diamond but want a proper cut grade, the AGS is the better choice. The GIA does not grade fancy cut diamonds based on cut, but the AGS does provide detailed reports for these unique shapes. So, shoppers seeking any shape that isn’t a round brilliant should consider whether the in-depth report of an AGS diamond is right for them.

Something to consider when choosing between AGS and GIA graded diamonds is price. While shopping, you may notice that AGS diamonds seem a bit pricier than most GIA stones. That’s because the average price of an AGS-graded diamond is slightly higher than a GIA gem, though it’s not a massive difference. Expect to pay roughly $10 more per carat when looking at diamonds of equal quality and size.

Where to shop for AGS diamonds

There are plenty of retailers who sell diamonds with AGS reports, but it’s important to choose a brand that you can trust. Here are two well-respected jewelers who have made a name for themselves by selling quality, AGS graded diamonds with the proper documentation to back up their specs:


We recommend starting with Whiteflash if you’re looking for an excellent diamond with AGS certification. Whiteflash boasts a beautiful line of premier diamonds known as A CUT ABOVE, and these diamonds all come with proper documentation that details their superior cuts.

The company’s strict multi-level control process for both rough and polished stones means A CUT ABOVE diamonds are an elite collection of gems with Super Ideal cuts. For more information on Super Ideal grading, you can read our thorough guide here.

Brian Gavin Diamonds

Another great place to start when shopping for AGS-graded diamonds is Brian Gavin. Similar to Whiteflash, Brian Gavin also features their own proprietary line of diamonds with Super Ideal cuts. Their line focuses on Hearts and Arrows diamonds that are cut for optimal light performance and sparkle.

This fifth-generation diamond cutter is well-known in the industry, and their work in Super Ideal cut diamonds is recognized internationally!

Final thoughts: Buying diamonds with AGS certification

AGS certification is definitely worth a look if you want a diamond that endured rigorous cut grading, which is a major factor in sparkle and light play. If you’re looking for your own AGS-graded diamond, start with online jewelers like Brian Gavin and Whiteflash, as these retailers offer a superior inventory of diamonds with AGS certification.

When it comes to whether you should choose a diamond with GIA or AGS certification, you’ll have to do a bit of soul searching to figure out which grading scale can provide your ideal diamond sparkle and quality. If you’re interested in learning more about GIA certification and how it stacks up to the AGS grading system, read our GIA certification guide before you make any final decisions!

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