How IGI Became the World Standard for Lab Grown Diamond Certification

By 2026, IGI holds roughly 65% of the global lab grown diamond certification market, a position built by being first to the category, staying specialized, and running a grading network that scaled alongside production. No other laboratory comes close to that share in the lab grown segment, and the gap has widened each year since CVD and HPHT production volumes started climbing in earnest.

Founded in Antwerp in 1975, IGI spent its first three decades certifying natural diamonds and finished jewelry across a multi-city laboratory network spanning Mumbai, Surat, New York, Bangkok, Tokyo, Dubai, and Hong Kong. The shift that changed everything came in 2005, when IGI became the first major gemological laboratory to offer full grading reports for lab grown diamonds. That head start compounded quickly, and the protocols IGI developed for disclosing growth method, post-growth treatment, and origin are now more developed than those of any other lab in the category.

Why did IGI commit to lab grown diamonds so early?

IGI moved because CVD and HPHT production was scaling with no independent grading standard in place. When Chemical Vapor Deposition and High Pressure High Temperature manufacturing began expanding in the early 2000s, retailers and consumers had no third-party report they could point to. GIA, which had built its reputation certifying natural diamonds since 1931 and developed the 4Cs grading system in the 1950s, did not begin issuing reports for lab grown diamonds until 2007. That two-year window mattered, but the deeper advantage was specialization.

IGI’s gemologists graded millions of lab grown stones through the 2000s and 2010s, developing specific expertise in the characteristics that distinguish CVD-grown diamonds (which can show graining or cloud-like formations) from HPHT-grown stones (which occasionally carry metallic flux inclusions). That accumulated experience cannot be replicated by scope expansion alone; it lives in the graders, the instruments, and the protocols they have refined over two decades.

What does an IGI lab grown diamond report actually document?

An IGI report covers the standard 4Cs: cut, color, clarity, and carat weight. For round brilliant cuts, IGI assigns an overall cut grade by comparing proportions against its own studies of brightness, fire, scintillation, and pattern. Color is graded on the D-to-Z scale under standardized lighting, with multiple independent graders assessing the same stone without sharing their results first. Clarity is assessed at 10x magnification, and a clarity plot diagram maps the location and type of every inclusion.

Beyond the 4Cs, the report documents polish and symmetry grades, fluorescence (graded from None to Very Strong), precise measurements, and the stone’s shape and cutting style. The section most buyers overlook is the one specific to lab grown diamonds: the growth method disclosure. The report explicitly states whether the stone was grown by CVD or HPHT, and notes whether any post-growth treatment was applied. Some CVD diamonds undergo a secondary HPHT annealing step after growth to correct color, which is an accepted industry practice, but one that must be disclosed. IGI discloses it. GIA’s simplified post-2025 report format omits this field entirely for lab grown stones.

Every IGI-certified lab grown diamond also receives a laser inscription on the girdle, a microscopic number that matches the report exactly and allows anyone to verify the stone’s identity through IGI’s online database.

How does IGI’s approach differ from GIA’s in 2026?

GIA remains the most respected name in natural diamond grading, and its conservative standards for mined stones are well established. For lab grown diamonds, however, the two labs have moved in different directions since October 2025.

GIA now grades lab grown diamonds on a simplified two-tier system, classifying stones as either “Premium” or “Standard” rather than assigning the traditional D-to-Z color grades and FL-to-I3 clarity grades. That change means a GIA report for a lab grown diamond no longer gives a buyer the granular information needed to compare stones on a like-for-like basis. IGI continues to use the full traditional grading scales for lab grown diamonds, providing the color letter, clarity grade, and cut score that buyers and retailers have relied on for decades.

The practical effect: if you are buying a lab grown diamond and want to know whether the stone is an F VS1 or a G VS2, an IGI report tells you. A post-October 2025 GIA report for the same stone does not.

Why has IGI certification become the retail default for lab grown diamonds?

IGI holds a 33% share of all diamond certifications globally and 65% of the lab grown diamond certification market specifically. In 2024, IGI’s revenue reached approximately $120.6 million, up 17% year over year, driven by rising demand for lab grown diamond certification. Retailers across the United States, Europe, and Asia stock IGI-certified stones because the report format is consistent, verifiable, and understood by buyers worldwide.

Consider what that consistency meant in a real transaction: when GIA switched to its two-tier format in October 2025, retailers who had stocked GIA-graded lab grown stones suddenly found buyers unable to compare those stones against IGI-graded inventory on a like-for-like basis. Several major US retailers responded by shifting their lab grown purchasing almost entirely to IGI-certified stock. The report format had become the shared language of the trade, and IGI was the one still speaking it.

For a shopper comparing two lab grown diamonds side by side, an IGI certificate is the document that makes that comparison possible. It was designed with lab grown diamonds in mind from the start, and it shows in the specifics: the growth method field, the treatment disclosure line, and the granular 4Cs grades that GIA’s current lab grown format no longer provides.

IGI Certification Earned Its Position by Doing the Work First

IGI did not become the industry default because of marketing or institutional weight. It got there by showing up in 2005 when no other major laboratory would, building grader expertise through volume, and refusing to simplify its reports when lab grown diamonds became mainstream enough to warrant shortcuts.

For buyers, the takeaway is practical: an IGI report on a lab grown diamond tells you the growth method, any post-growth treatment, and the full 4Cs in a format that has been consistent for nearly two decades. A retailer stocking IGI certified lab grown diamonds gives you that document as the starting point for every purchase decision. The report is the record. Everything else follows from it.

Frequently Asked Questions

Is IGI certification trustworthy for lab grown diamonds?

IGI has been grading lab grown diamonds since 2005, longer than any other major laboratory, and currently holds approximately 65% of the global lab grown diamond certification market. Its reports are accepted by major retailers worldwide and use the same independent multi-grader process applied to natural diamonds, with one grader’s result never shared with the next before they assess the stone.

What is the difference between an IGI and a GIA certificate for a lab grown diamond in 2026?

The key difference is grading detail. IGI continues to assign traditional D-to-Z color grades and FL-to-I3 clarity grades for lab grown diamonds. Since October 2025, GIA replaced those grades with a simplified two-tier system, “Premium” or “Standard,” which gives buyers significantly less information when comparing stones and omits the growth method disclosure field that IGI includes.

Does an IGI report tell you whether a lab grown diamond was treated after growth?

IGI’s report explicitly states the growth method, either CVD or HPHT, and discloses whether the stone underwent any post-growth treatment, such as a secondary HPHT annealing step to improve color. This disclosure appears in the Comments section of the full report. It is the part most buyers skip, and skipping it means missing whether the color grade reflects the stone as grown or as treated.

Why do most lab grown diamond retailers use IGI rather than GIA?

IGI specialized in lab grown diamond grading earlier than any other major lab, building specific expertise in the characteristics of CVD and HPHT stones through two decades of volume. Its reports are consistent across a global laboratory network and provide the granular grading data, including growth method and treatment status, that retailers and buyers need to price and compare stones accurately.

Can I verify an IGI certificate online?

Every IGI-certified lab grown diamond receives a unique report number, typically a nine-digit alphanumeric code, and a matching laser inscription on the girdle. Entering the report number on IGI’s website confirms the certificate is authentic and that the grades on the document match the stone in front of you. It takes about thirty seconds and is the single fastest way to rule out a counterfeit or misrepresented stone.