1. Background: Lab-Grown Diamond Certification
Lab-grown diamonds (LGDs) are chemically and physically the same as natural diamonds but are created in controlled laboratory environments using methods like High Pressure High Temperature (HPHT) or Chemical Vapor Deposition (CVD). As production of LGDs has surged over the last decade, certification labs have adapted their approaches to grading and reporting these stones.
A key part of this ecosystem is independent third-party certification, which aims to provide objective information on a diamond’s quality characteristics. Two of the most recognized gemological laboratories are:
- The Gemological Institute of America (GIA) — historically the most prestigious authority on diamond grading, especially for natural stones.
- The International Gemological Institute (IGI) — an independent, for-profit laboratory that pioneered lab-grown diamond grading and has dominated this segment.
2. Market Share and Certification Volume
Quantitative data comparing the number of lab-grown stones certified by GIA vs. IGI isn’t published directly by the labs, but credible industry sources and reports paint a clear picture of relative market penetration:
IGI’s Dominance in LGD Certification
- IGI has long been the primary certification authority for lab-grown diamonds and is widely considered the market leader.
- Recent industry analysis estimates that IGI certifies roughly around 65–80% of lab-grown diamonds globally — making it the most widely used lab in the LGD sector.
- IGI’s leadership is reflected in its early entry (starting to grade LGDs as early as 2005) and its broad adoption by large retailers.
GIA’s Smaller Share
- GIA focused primarily on natural diamonds for decades and only gradually accepted lab-grown stones into its grading services.
- Estimates suggest GIA’s share of LGD certification is significantly smaller — often cited as less than ~15% of the market compared to IGI’s majority share.
- Some industry observers note that GIA grades fewer than ~5% of lab-grown diamonds at times, with most consumers and retailers opting for IGI certificates instead.
Additionally, broader industry research indicates that overall certification penetration for lab-grown diamonds is higher than for natural stones, with around ~70% of LGDs being certified in 2023. This contrasts with ~65% certification penetration across all diamonds (natural and lab-grown), driven largely by the larger sizes and retail demand for LGDs.
3. Grading Practices: Traditional 4Cs vs. New Frameworks
IGI: Traditional 4Cs Reporting
- IGI continues to use the traditional diamond grading criteria — Cut, Colour, Clarity, and Carat (4Cs) — for lab-grown diamonds, providing detailed reports that include specific letter grades for these characteristics.
- IGI’s reports often include additional information such as the growth method (HPHT or CVD), clarity plots, and laser inscribed report numbers on the diamond’s girdle.
- This detailed grading makes IGI the preferred standard in the LGD marketplace, especially for retail and resale transactions where buyers want specific quality data.
GIA: Shift Away from Traditional 4Cs
Until late 2025, GIA graded lab-grown diamonds using the same 4Cs framework it historically applied to natural diamonds. However:
- Starting October 1, 2025, GIA discontinued issuing full 4Cs grading certificates for lab-grown diamonds. Instead, it moved to a simplified reporting system that categorizes LGDs broadly as “Premium” or “Standard”, or does not issue a grade to stones that fail minimum quality criteria.
- Under this new system, GIA’s reports for lab-grown stones no longer provide specific letter grades (e.g., D–Z colour, VVS1, VS2 clarity) — a significant departure from traditional diamond grading nomenclature.
- GIA’s rationale is that most lab-grown diamonds fall within a very narrow range of colour and clarity, making detailed grading less meaningful for differentiation.
This change has broad industry implications:
- It simplifies GIA lab-grown reports and signals a strategic shift away from detailed grading for LGDs.
- By contrast, IGI continues to emphasize detailed grading with full 4C metrics, reinforcing its role as the go-to certifier for lab-grown stones.
4. Current Status of Grading Certificates
GIA
- GIA still accepts and grades lab-grown diamonds, but under the new framework — issuing category-based rather than detailed 4Cs certificates.
- All traditional detailed 4Cs certificates issued for lab-grown diamonds remain valid, but no new ones are issued after the change took effect in late 2025.
- The simplified “Premium”/“Standard” system is GIA’s current position for lab-grown diamond certification.
IGI
- IGI continues issuing full grading certificates using the standard 4Cs system for lab-grown diamonds.
- It remains a leading certification body for both natural and lab-grown stones, and is often preferred by retailers and consumers who want comprehensive quality information.