IGI Laboratory-Grown Diamond Report

The IGI (International Gemological Institute) Laboratory-Grown Diamond Report is the most common grading credential for lab-grown diamonds sold through US retail channels. IGI, headquartered in Antwerp with major labs in Mumbai and New York, processes the majority of lab-grown diamond inventory worldwide; its reports trade at near-par with GIA Laboratory-Grown Diamond Reports in the US retail market.

The IGI report uses the same color scale as natural diamond grading — D (colorless) through Z (light yellow) — and the same eleven-grade clarity scale (FL, IF, VVS1, VVS2, VS1, VS2, SI1, SI2, I1, I2, I3). Cut grade on rounds runs Excellent through Poor on the same scale. The grading methodology, master stones, and inspection process are nominally equivalent to GIA's; the difference is in calibration tolerance, where IGI is widely understood in the trade to grade slightly more leniently than GIA at the borderlines between adjacent grades.

The growth method (CVD or HPHT) is disclosed on every IGI lab-grown report under the "Treatment" or "Origin" section. Post-growth treatments — most commonly post-growth HPHT to remove brown tint from CVD stones — are separately disclosed. The growth method does not affect price in retail; the disclosure is informational.

IGI lab-grown reports carry a laser inscription on the girdle reading "Lab Grown" or "LG" followed by the IGI report number. The inscription is verifiable against the IGI online database; the database lookup is the standard verification path for a buyer or seller checking authenticity. IGI also issues digital reports accessible by QR code on the physical report.

IGI was the first major lab to issue dedicated lab-grown diamond reports in commercial volume, beginning in the early 2010s. The early-mover position gave IGI substantial market share in the lab-grown channel by the time GIA expanded its lab-grown grading program in 2020. As of 2026, IGI remains the dominant lab for lab-grown commercial grading by volume; GIA Laboratory-Grown Diamond Reports carry a 5% to 10% retail premium over IGI at the same paper grade because of GIA's natural-diamond brand recognition.

For natural diamond grading, IGI issues standard Diamond Grading Reports on the same D-Z and FL-I3 scales as GIA. IGI natural reports trade at a small discount to GIA naturals (typically 5% to 10%) at the same paper grade in the US retail channel. IGI Antwerp grading is regarded as tighter than IGI Mumbai grading; the trade sometimes specifies "Antwerp IGI" for higher-value naturals.