What IGI is: structure, scale, and reach
IGI is a commercial for-profit laboratory, unlike GIA, which is a non-profit educational institution. This structural difference is the foundation of the grading difference discussed below. IGI's business model depends on attracting diamond submissions; GIA's depends on educational and grading revenue from a non-profit mandate.
IGI was founded by Roland Lorie in Antwerp in 1975 (IGI institutional information, igi.org). From Antwerp, it expanded to other major diamond trading centres and jewellery markets, New York, Mumbai, Surat, Tel Aviv, Hong Kong, Tokyo, Dubai, and others. In India, IGI has become the dominant laboratory by volume because of its accessible fees, multiple India office locations, and faster turnaround than GIA Mumbai for high-volume commercial goods.
IGI grades all types of gemstones and jewellery, not only diamonds. It issues reports for coloured gemstones, pearls, jewellery appraisals, and other gem products. GIA also offers services beyond diamond grading, but diamond grading is GIA's primary institutional identity. IGI's broader service range makes it more commercially versatile but also means its reputation is distributed across multiple product categories rather than concentrated on diamond grading.
IGI in India: the primary laboratory for Indian trade
In the Indian context, IGI is more visible and accessible than GIA. IGI operates multiple India offices: the primary grading laboratory is in Zaveri Bazaar, Mumbai, the heart of India's jewellery and diamond retail trade. Additional India offices include Surat (serving the cutting industry directly), Delhi, Jaipur, Coimbatore, and others (IGI India office locations, igi.org).
The Zaveri Bazaar location is significant: the laboratory is embedded in the retail and wholesale jewellery district, accessible to small and medium jewellers who make up the bulk of the Indian trade. GIA's Mumbai laboratory at BKC is more distant from the traditional jewellery market. For a small jeweller in Zaveri Bazaar submitting a ₹80,000 stone for certification, IGI is the practical choice, accessible, affordable, and with turnaround times suited to commercial operations.
The Surat IGI office serves the cutting industry, manufacturers who want IGI certification for their polished goods before sale. The concentration of diamond manufacturing in Surat means a large volume of IGI-certified goods originates from Surat factory submissions (GJEPC industry data, gjepc.org; IGI Surat office, igi.org).
The IGI Diamond Grading Report: what it covers
The IGI Diamond Grading Report uses the same grading scales as GIA, D-Z colour, FL-I3 clarity, and Excellent-Poor cut for round brilliants. The report shows the same basic information: shape and cutting style, measurements, carat weight, cut/polish/symmetry grades, colour grade, clarity grade, fluorescence, a proportions diagram, and a clarity plot. The IGI report also includes laser inscription of the report number on the diamond's girdle.
For lab-grown diamonds, IGI reports clearly state "Laboratory-Grown" on the certificate and in the girdle inscription, there is no ambiguity about whether an IGI lab-grown certificate refers to a natural or synthetic stone (IGI Diamond Grading Report format documentation, igi.org).
The IGI report can be verified online at igi.org by entering the report number. The same verification should be performed for any IGI-certified diamond as for GIA: enter the report number online, confirm grades match the physical certificate, and confirm the girdle inscription under a 10× loupe.
The grading difference from GIA: the honest account
The documented difference between IGI and GIA grading is approximately one colour grade and one clarity grade more generous for IGI on average, meaning a stone graded F/VVS2 by IGI would typically receive a grade of approximately G/VS1 or G/VS2 from GIA. This is a statistical average across a population of stones; individual stones may fall on either side of this average.
The source of this difference is structural rather than intentional. IGI is a commercial laboratory whose business depends on attracting submitters. On borderline stones that could fall on either side of a grade boundary, interpretation tends toward the higher grade, producing better commercial outcomes for the submitting manufacturer. Over a large population of stones, this marginal bias creates the documented average difference (Rapaport Magazine market analysis, various 2010–2025; IDEX Online market commentary 2015–2025).
This does not mean IGI certificates are fake or unreliable as identification documents. An IGI report accurately describes the stone it was issued for, the report number on the girdle matches the certificate, the measurements are accurate, the cut grade is based on real proportion measurements. The difference is in the colour and clarity grade interpretation at the margin.
Why the market has priced in the difference
The diamond trade globally, Antwerp, New York, Tel Aviv, Surat, Mumbai, applies a consistent discount to IGI-certified stones relative to GIA-certified stones of the same stated grades. This discount, typically 8 to 15 percent depending on the quality combination and market segment, reflects the trade's collective understanding that the actual quality of an IGI-graded stone is somewhat lower than its stated grade relative to GIA standards (Rapaport Diamond Report price data, Rapaport Group, New York; IDEX Online price data). The discount has existed consistently across multiple market cycles and has not disappeared despite IGI's improvements in grading consistency.
IGI and lab-grown diamonds: the primary standard
For lab-grown diamonds, IGI occupies a different position than for natural diamonds. IGI is the dominant certification laboratory for lab-grown goods globally, the vast majority of CVD and HPHT lab-grown diamonds in the Indian and international market carry IGI certificates. This dominance reflects IGI's early positioning in the lab-grown market and its accessibility to the manufacturers who produce lab-grown goods, many of whom are in Gujarat.
The grade generosity concern for natural diamonds is less significant for lab-grown goods. Lab-grown diamonds are produced to specific quality targets by manufacturers who know what they are making, the quality distribution is more controlled than natural rough. IGI's consistency for lab-grown is considered better than for natural diamonds, and the lab-grown market does not apply the same discount to IGI-certified goods that the natural market applies (Rapaport Magazine lab-grown market analysis 2022–2025).
For consumers buying lab-grown diamonds, IGI certification from igi.org (verified by report number and girdle inscription) is the appropriate standard at any price point. The laboratory clearly distinguishes lab-grown from natural on all documentation, there is no risk of a lab-grown stone being confused with a natural stone on an IGI report.
When IGI certification is appropriate
The following guidance applies specifically to the Indian market in 2026 and is based on the grade accuracy considerations and price points described above.
Natural diamond below ₹2–3 lakh, the absolute grade-gap exposure is manageable and GIA fees represent a higher proportion of purchase value.
Lab-grown diamonds at any price, IGI is the industry standard; its lab-grown grading is more consistent than its natural grading.
Commercial goods for trade purposes, manufacturers and dealers who need accessible, cost-effective certification for high volumes of commercial quality goods.
When the stone has been independently assessed, if a GIA-qualified gemologist has confirmed the stone's characteristics align with the IGI grades, the certificate is adequate for insurance and identification purposes.
Natural diamond above ₹5 lakh, the grade gap exposure is material (₹50,000–₹2,50,000+ depending on size); GIA certification provides the necessary grade accuracy.
Investment-grade purchase, secondary market values natural diamonds on GIA grades, not IGI; an IGI stone resells at GIA-equivalent quality prices.
Any purchase where grade accuracy is the primary trust basis, if the buyer is relying on the certificate rather than independent assessment, GIA provides stronger protection for high-value goods.
How to verify an IGI certificate
The IGI verification process is equivalent to GIA's:
Step 1: Note the report number from the physical IGI certificate.
Step 2: Go to igi.org and use the report lookup (certificate verification) service. Enter the report number. The database returns the stone's grades, measurements, and carat weight as recorded by IGI. Confirm they match the physical certificate.
Step 3: Under a 10× loupe, find the girdle inscription. The inscription should include the IGI report number. Confirm it matches the certificate number.
Step 4: Confirm the stone's physical measurements (stated on the IGI certificate) are approximately consistent with a stone of the stated carat weight and proportions.
For lab-grown diamonds: the IGI certificate will clearly state "Laboratory-Grown" in the report header and on the girdle inscription. If a certificate claimed to be for a natural stone does not have this notation and verifies correctly at igi.org, the natural claim is supported by the IGI certification.
Primary sources cited here
IGI institutional information. Available at igi.org. International Gemological Institute, Antwerp. [Founded 1975, Roland Lorie, commercial structure, India office locations (Zaveri Bazaar, Surat, and others), lab-grown certification services, certificate verification service.]
Rapaport Magazine. Rapaport Group, New York. Various issues 2010–2025. [Grade difference documentation; IGI market discount data; lab-grown certification market analysis 2022–2025.]
IDEX Online. IDEX, Israel. Market commentary and price data, 2015–2025. [IGI-GIA market discount confirmation; lab-grown market share documentation.]
GJEPC (Gem and Jewellery Export Promotion Council). gjepc.org, Mumbai. [India diamond industry data; Surat cutting industry context for IGI Surat office significance.]
IGI Diamond Grading Report format documentation. Available at igi.org. [Report format, lab-grown notation standard, girdle inscription standard, verification service.]
Frequently asked questions
Is an IGI certificate valid for insurance purposes?
Yes. An IGI Diamond Grading Report is accepted by Indian insurance companies as identification documentation for diamond jewellery insurance. The report serves as the specification document for the insured item, its measurements, carat weight, and stated grades are recorded in the policy. Note that the insured value is typically set at the purchase price or an independent appraisal value, not derived directly from the grade on the certificate.
Why do most Indian jewellers use IGI rather than GIA?
Multiple factors: IGI has much more India office locations than GIA (Zaveri Bazaar, Surat, and others vs GIA's single Mumbai BKC location); IGI fees are generally lower than GIA for equivalent services; IGI turnaround times are typically faster; and the Indian commercial trade has built long relationships with IGI over decades. For the majority of Indian diamond trade transactions, commercial goods below ₹2 lakh, IGI serves the practical certification need efficiently. The limitation only becomes significant for higher-value goods where grade accuracy has a material rupee impact.
Does IGI grade coloured diamonds?
Yes. IGI grades fancy colour diamonds (natural and lab-grown) and issues colour grading reports for fancy colour stones. Fancy colour grading, assessing the hue, saturation, and tone of yellow, pink, blue, and other coloured diamonds, is a distinct service from white diamond grading. For fancy colour natural diamonds of significant value, GIA's colour grading is also available and provides the most internationally recognised reference. For lab-grown fancy colour diamonds, IGI is the primary certification standard as with colourless lab-grown goods.