Other Lab Diamond Certifications: How IGI and GIA Compare to GCAL, AGS, and HRD

Five grading labs have shaped the lab-grown diamond certification landscape: IGI, GIA, GCAL, AGS, and HRD Antwerp. Of these, IGI is the strongest practical choice for lab-grown diamond buyers in 2026, because it is the only major lab that still issues full 4Cs reports with specific color and clarity grades for lab-grown stones. GIA switched to a simplified two-tier system in October 2025, AGS closed its independent laboratory in December 2022, and HRD Antwerp stopped certifying loose lab-grown diamonds for commercial sale as of 2026. GCAL remains a credible option with a uniquely rigorous cut standard, but its inventory is narrower and stones carry a premium. Understanding what each lab actually grades, and what changed recently, is what separates a confident purchase from a guesswork one.

What does IGI actually grade on a lab-grown diamond report?

IGI is the dominant certification body for lab-grown diamonds worldwide, and its reports are the most detailed available for this category. An IGI lab-grown diamond report covers the full 4Cs: cut, color, clarity, and carat weight. Color is graded on the D-to-Z scale; clarity runs from Flawless (FL) to Included (I3). The report also identifies the growth method (CVD or HPHT), notes fluorescence, and laser-inscribes the report number on the diamond’s girdle so you can verify it independently.

For round brilliants, IGI assigns an overall cut grade. For fancy shapes such as ovals, cushions, and pears, IGI also issues cut grades, which is an advantage over GIA, which does not yet provide cut grades for most fancy shapes.

The one legitimate criticism of IGI is that its grading tends to run slightly more lenient than GIA’s, particularly for natural diamonds. Industry consensus places the gap at roughly one grade for color and clarity. For lab-grown stones specifically, however, that gap narrows considerably, with side-by-side comparisons in 2026 showing IGI grades aligning closely with other major labs when assessing equivalent lab-grown diamonds.

How did GIA change its lab-grown grading, and does it matter?

GIA is the most recognized name in gemological grading, built on decades of natural diamond certification. For lab-grown diamonds, the picture shifted significantly in October 2025, when GIA replaced specific 4Cs grading with a two-tier system that labels stones only as “Premium” or “Standard.” That means specific grades like “D color” or “VVS2 clarity” no longer appear on GIA’s lab-grown reports.

For a buyer comparing two lab-grown stones side by side, that loss of granularity is a practical problem. You cannot compare a “Premium” stone from one retailer to a “Premium” stone from another and know whether you are looking at an E/VVS1 or an H/SI1. IGI, by contrast, continues to apply the full D-to-Z color scale and FL-to-I3 clarity scale to every lab-grown stone it grades.

GIA probably still makes sense if you are buying a high-value natural diamond and want the strictest benchmark on the report. For lab-grown diamonds in 2026, it is a less useful document than it was two years ago.

What makes GCAL 8X different from every other certification?

GCAL (Gem Certification and Assurance Lab), based in New York, occupies a specific niche: it is the only lab that backs its grading with a financial guarantee. Its flagship product for lab-grown diamonds is the 8X Ultimate Cut Grade, and the name describes exactly what it measures.

To earn an 8X designation, a diamond must receive an “Excellent” grade in all eight of the following categories: polish, external symmetry, proportions, optical brilliance, fire, scintillation, optical symmetry, and Hearts and Arrows. GIA’s cut grade, by comparison, draws on seven factors. More than 50% of round brilliant cut diamonds receive an “Excellent” cut grade from traditional grading labs, but fewer than 1% of those qualify as 8X.

GCAL stones tend to carry a price premium for two reasons: the certification itself costs more, and only diamonds that genuinely meet the standard can carry the designation. For buyers who want the highest cut precision available and are willing to pay for it, GCAL 8X is probably the most rigorous option on the market in 2026. For buyers who want the widest selection at the most accessible prices, IGI-certified inventory is far larger.

Is AGS certification still an option for lab-grown diamonds?

AGS Laboratories closed its independent grading operations in December 2022, after 27 years. GIA acquired the lab’s intellectual property, technology, and Las Vegas facility, repurposing it as a cut research center. The AGS grading system, including its 0-to-10 scale where 0 represents Ideal, and its scientific approach to light performance via computerized ray-tracing, no longer exists as a standalone certificate.

Existing AGS reports issued before December 2022 remain valid and verifiable through the AGS website. New stones, however, can only receive an AGS Light Performance assessment as a GIA supplement, not as a standalone grading report. For most lab-grown diamond buyers, this is a closed door: AGS-specific grading is no longer a live purchasing option. The AGS methodology did contribute meaningfully to the industry’s understanding of cut quality, and its influence shows clearly in how GCAL’s 8X system was later developed.

Why did HRD Antwerp stop certifying loose lab-grown diamonds?

HRD Antwerp, the grading laboratory of the Antwerp World Diamond Centre, became the first major international lab to formally exit commercial certification of loose lab-grown diamonds as of 2026. The lab had been certifying lab-grown stones since 2013, but its CEO Ellen Joncheere stated plainly: “As of 2026, we will no longer issue quality certificates for loose synthetic diamonds intended for commercial use.”

The stated reason was consumer confusion created by using identical terminology and certificate formats for both natural and lab-grown stones. HRD’s business in lab-grown diamonds had been small (described internally as a “mid-single-digit” percentage of total volume), and the decision aligns with Antwerp’s broader identity as a center for natural diamond trade.

For buyers in the United States, HRD was already a secondary name compared to IGI and GIA. Its exit from loose lab-grown certification makes it a non-factor for anyone shopping for a lab-grown stone in 2026. Jewelry pieces containing lab-grown diamonds can still be submitted for HRD certification, but loose stones cannot.

IGI Is the Grading Standard That Holds Up in 2026

The certification landscape for lab-grown diamonds has narrowed considerably. AGS no longer issues standalone reports. HRD has exited loose lab-grown certification. GIA’s simplified “Premium/Standard” system strips out the specific grades that make a report useful for comparison shopping. GCAL 8X is the most rigorous cut standard available, and worth the premium for buyers who prioritize light performance above everything else.

For most lab-grown diamond buyers, IGI is the grading report that delivers the most practical information: full 4Cs grades, growth method disclosure, laser inscription, and wide retailer acceptance. That combination is why it dominates the category. At Ouros Jewels, every certified stone comes with an IGI report, so the grades on the page reflect a consistent, verifiable standard. If you want to see what an IGI-certified stone looks like in a finished setting, the IGI Certified Round Lab Grown Diamond Stud Earrings are a good starting point for understanding how the grades translate to a real piece.

Frequently Asked Questions

Can I trust an IGI-certified lab-grown diamond the same way I would trust a GIA-certified natural diamond?

IGI is a credible, widely accepted grading lab with decades of experience and a large network of laboratories. For lab-grown diamonds specifically, IGI’s full 4Cs reports are more detailed than what GIA currently issues for lab-grown stones. The grades are verifiable online using the laser-inscribed report number, and insurers and resellers broadly recognize IGI certificates.

If a lab-grown diamond has an older AGS certificate, is that report still valid?

Yes. AGS reports issued before December 2022, when the lab closed its independent grading operations, remain valid and can be verified through the AGS website. The diamond’s grades have not changed. The only practical limitation is that you cannot obtain a new AGS standalone report for any stone today, since GIA now administers the AGS methodology as a supplement rather than a separate certificate.

What does it mean when a diamond is described as GCAL 8X certified?

A GCAL 8X diamond has received an “Excellent” grade in all eight of the following cut categories: polish, external symmetry, proportions, optical brilliance, fire, scintillation, optical symmetry, and Hearts and Arrows. Fewer than 1% of diamonds that receive a standard “Excellent” cut grade from other labs qualify for the 8X designation. GCAL also backs the certificate with a financial guarantee, which no other major grading lab offers.

Why does it matter which lab certifies a lab-grown diamond if the stone is the same?

Grading standards differ between labs, and those differences show up in the grades printed on the report. A stone graded by one lab as “VS1/G” might receive “VS2/H” from a stricter lab. The certificate is the document that travels with the stone through resale, insurance, and appraisal, so the lab’s credibility and grading consistency affect the stone’s long-term value and your ability to compare it accurately against other diamonds.

Is HRD Antwerp certification worth seeking out for a lab-grown diamond purchased in the US?

No. HRD Antwerp stopped issuing quality certificates for loose lab-grown diamonds intended for commercial sale as of 2026. Even before that decision, HRD was primarily encountered in continental Europe rather than the US market. For American buyers, IGI and GCAL are the two active certification options worth considering for lab-grown diamonds in 2026.