IGI Certification Explained

If you've recently shopped for a diamond — especially a lab-grown one — you've almost certainly seen the letters IGI stamped on the certificate. For many buyers, that's where the questions start. What is IGI? Is it trustworthy? Is it as good as GIA? Why do most lab-grown diamonds carry IGI certification?

This guide answers every question buyers ask us at Reverra Jewels — clearly, honestly, and without the marketing spin.

At Reverra Jewels, we operate from the heart of the New York Diamond District at 15 W 47th Street, where we handcraft fine jewelry that bridges generations of Indian artisanal tradition with the standards of the modern American market. Every lab-grown diamond we set comes with IGI certification, because we believe documentation isn't a feature — it's a promise.

Here's everything you need to know about IGI before you buy.

Quick Answer: What Is IGI?

IGI (International Gemological Institute) is one of the world's largest and most trusted independent diamond grading laboratories. Founded in 1975 in Antwerp, Belgium, it grades natural diamonds, lab-grown diamonds, colored gemstones, and finished jewelry. Today, IGI is best known as the global leader in lab-grown diamond certification, certifying the majority of lab-grown diamonds sold worldwide.

When you see an IGI report, you're looking at an internationally recognized, independent quality assessment — the same standard used by jewelers, retailers, and diamond traders across the U.S., Europe, India, and the Middle East.

The History of IGI

IGI was founded in 1975 in Antwerp, Belgium — the historic heart of the global diamond trade. Antwerp has been the world's premier diamond cutting and trading hub for more than 500 years, so it's no coincidence the institute was born there.

What began as a regional grading lab has grown into a truly global operation. Today, IGI runs over 30 laboratory and education locations worldwide, including major facilities in:

•        New York (USA)

•        Antwerp (Belgium)

•        Mumbai, Surat, Delhi, Bangalore, Chennai, Kolkata, Ahmedabad, Jaipur, Hyderabad, Thrissur (India)

•        Bangkok (Thailand)

•        Dubai (UAE)

•        Hong Kong and Shanghai (Greater China)

•        Tokyo (Japan)

•        Tel Aviv (Israel)

•        Toronto (Canada)

This global footprint matters more than most buyers realize. It means an IGI-certified diamond carries weight everywhere — whether you're buying it on 47th Street in New York, gifting it in Mumbai, or insuring it in London.

IGI also pioneered something that changed the modern diamond market forever: it was among the first major laboratories to develop a complete grading framework specifically for lab-grown diamonds. While other labs hesitated, IGI built the standards that the entire lab-grown industry now relies on.

What Does IGI Actually Do?

IGI offers four core services:

1. Diamond Grading

Both natural and lab-grown diamonds are evaluated using the universal 4Cs — Cut, Color, Clarity, and Carat Weight — along with additional factors like polish, symmetry, and fluorescence.

2. Colored Gemstone Identification

Sapphires, rubies, emeralds, and other colored stones are tested to confirm authenticity, identify treatments, and document quality.

3. Jewelry Identification & Appraisal

Unlike some labs, IGI also certifies finished jewelry pieces — meaning your engagement ring, tennis bracelet, or pair of solitaire studs can be evaluated as a complete piece, not just the loose stone before setting.

4. Gemological Education

IGI runs schools that train the next generation of gemologists, jewelry designers, and diamond graders. Their courses are recognized across the global trade.

Why IGI Dominates Lab-Grown Diamond Certification

If you're shopping for a lab-grown diamond, you'll see IGI everywhere. There's a reason for that.

When lab-grown diamonds first entered the market at scale in the 2010s, most major labs were slow to develop dedicated grading frameworks. IGI moved fast. It built specific protocols to evaluate CVD (Chemical Vapor Deposition) and HPHT (High Pressure High Temperature) lab-grown diamonds, and it began issuing detailed reports that included:

•        Whether the diamond is natural or lab-grown

•        The growth method (CVD or HPHT)

•        Any post-growth treatments

•        Full 4Cs grading on the same scale used for natural diamonds

That early leadership made IGI the default lab for the lab-grown supply chain — from growers in India and the U.S., to wholesalers, to retailers like Reverra Jewels. Today, the vast majority of lab-grown diamonds sold in jewelry stores worldwide carry an IGI report.

For lab-grown buyers, IGI offers something especially valuable: transparency about origin. The growth method is right there on the certificate. You know exactly what you're getting.

What's Inside an IGI Diamond Report

An IGI grading report is one of the most detailed documents in the diamond industry. Here's what every report includes:

Identification Information

•        Report Number — a unique ID for your specific certificate

•        Certification Date — when the diamond was examined

•        Diamond Description — natural or laboratory-grown

•        Growth Method (lab-grown only) — CVD or HPHT

•        Treatments — any post-growth or post-mining enhancements

The 4Cs

•        Carat Weight — measured to the hundredth of a carat

•        Color Grade — D (colorless) to Z (light yellow/brown)

•        Clarity Grade — Flawless (FL) to Included (I3)

•        Cut Grade — Excellent to Poor (round brilliants)

Physical Details

•        Shape and Cutting Style — round, oval, princess, emerald, radiant, etc.

•        Measurements — length × width × depth in millimeters

•        Polish — the smoothness of the facet surfaces

•        Symmetry — how precisely facets align

•        Fluorescence — UV reaction (None, Faint, Medium, Strong)

Visual Documentation

•        Clarity Plot — a diagram showing the location of every inclusion and blemish

•        Proportions Diagram — table %, depth %, crown angle, pavilion angle, girdle thickness, culet size

Security Features

•        Laser Inscription — IGI's proprietary Laserscribe® technology engraves the report number microscopically on the diamond's girdle, invisible to the naked eye but verifiable under magnification

•        Online Verification — every report can be checked at no cost on igi.org

How IGI Grades a Diamond

Understanding the process behind an IGI report helps you trust what's on the paper.

Step 1 — Receipt and Sealing. Each diamond arrives at an IGI lab anonymously, sealed in a tamper-evident envelope. Graders don't know who submitted the stone.

Step 2 — Initial Measurement. Trained gemologists measure carat weight to four decimal places and physical dimensions to the hundredth of a millimeter using calibrated instruments.

Step 3 — Color Grading. The diamond is compared, face-down, against a master set of reference stones in a controlled lighting environment. Multiple graders evaluate independently.

Step 4 — Clarity Grading. Under 10x magnification, gemologists identify and plot every inclusion and blemish. Clarity is graded based on size, location, nature, and visibility.

Step 5 — Cut, Polish & Symmetry. For round brilliants, the cut is graded using proportions, polish, and symmetry data. Other shapes receive polish and symmetry grades.

Step 6 — Verification. Multiple graders' results are compared. If grades disagree, the diamond is re-evaluated. Only when consensus is reached does the report get issued.

Step 7 — Inscription. If requested, IGI laser-inscribes the report number on the girdle so the certificate and the diamond can never be separated.

This anonymity-and-consensus process is what gives an IGI report its value — no single grader's opinion controls your diamond's grade.

Is IGI Trustworthy? An Honest Answer

Yes — and here's the nuanced version of that answer.

Where IGI excels:

•        Lab-grown diamonds. IGI is the global standard. Its grading is consistent, detailed, and trusted across the lab-grown supply chain.

•        Faster turnaround. IGI's reports are typically issued faster than competing labs, which keeps the diamond pipeline moving and helps keep retail prices lower.

•        Global recognition. An IGI report is accepted in essentially every major diamond market in the world.

•        Detailed reporting. IGI reports often include more granular information about treatments, growth methods, and finished jewelry than competing labs.

The honest caveat:

For natural diamonds, IGI has historically been considered slightly more lenient than GIA on color and clarity grading. A diamond IGI grades as G/VS1 might receive H/VS2 from GIA. This isn't fraud — it's a known calibration difference between two reputable labs. For lab-grown diamonds, this difference is far less pronounced because IGI's lab-grown standards are the industry benchmark.

The bottom line: IGI is a legitimate, internationally recognized grading authority. For lab-grown diamonds, it's the lab to look for. For natural diamonds, you may also want to consider GIA — particularly for higher-value stones or pieces you may want to resell.

How to Verify an IGI Certificate

This is the most important step most buyers skip. Always verify your IGI certificate before purchase. It takes 30 seconds.

Step 1. Go to igi.org.

Step 2. Click "Verify Your Report."

Step 3. Enter the report number from your certificate.

Step 4. Confirm the displayed grades match the physical certificate and the diamond.

If the report number doesn't return a match — or the details don't align — walk away. Every legitimate IGI report can be verified online for free.

If your diamond is laser-inscribed (most IGI-certified stones are), a jeweler can show you the inscription under magnification. The number on the diamond should match the number on the certificate.

IGI Grading Scales: A Quick Reference

Color Scale

Clarity Scale

Cut, Polish & Symmetry Scales

Round brilliants and finishing grades both use the same five-tier scale:

Excellent → Very Good → Good → Fair → Poor

Fluorescence Scale

None → Faint → Medium → Strong → Very Strong

What to Look For When Buying an IGI-Certified Diamond

When you're evaluating an IGI-certified diamond — especially online — here's a practical checklist:

Confirm the report is current. A report number alone isn't enough. Verify it on igi.org.

Match the inscription to the report. Ask the jeweler to show you the laser inscription on the girdle. The numbers must match.

Read the comments section. This is where treatments, unusual features, or notes about the stone get documented. Don't skip it.

For lab-grown, check the growth method. CVD and HPHT are both legitimate, but the certificate should state which one. Transparency here is non-negotiable.

Cross-check the 4Cs against the price. A G/VS1 lab-grown round at a suspiciously low price may have other issues (poor fluorescence, poor symmetry, or visible inclusions despite the grade). The certificate tells you the full story — read all of it, not just the headline.

Buy from a jeweler who explains, not deflects. A reputable jeweler will walk you through every line of the certificate. At Reverra Jewels, we do this for every diamond we sell.

Frequently Asked Questions

Is IGI as good as GIA?

For lab-grown diamonds, IGI is the industry leader and the standard most lab-grown stones are graded against. For natural diamonds, GIA is often considered the stricter benchmark, but IGI is still a fully reputable, internationally recognized lab.

Why are most lab-grown diamonds IGI certified?

IGI was among the first major labs to develop comprehensive grading standards for lab-grown diamonds, so the entire lab-grown supply chain — growers, wholesalers, and retailers — standardized around IGI reports.

Can IGI certificates be faked?

The certificates themselves can be counterfeited, which is exactly why online verification at igi.org exists. Always verify the report number directly on IGI's website before any purchase.

Does an IGI-certified diamond hold its value?

Lab-grown diamonds — IGI-certified or otherwise — generally don't appreciate the way natural diamonds can, because lab production capacity continues to grow. But IGI certification ensures you're paying for the quality you're getting at the time of purchase, which is what matters most for fine jewelry you'll wear and enjoy.

What's the difference between CVD and HPHT lab-grown diamonds?

Both are real diamonds, chemically identical to natural ones. CVD (Chemical Vapor Deposition) grows diamonds layer by layer in a vacuum chamber. HPHT (High Pressure High Temperature) recreates the earth's natural diamond-forming conditions. Both methods produce beautiful, certifiable diamonds — IGI grades both equivalently.

Does IGI certify finished jewelry?

Yes. Unlike some labs that grade only loose stones, IGI also issues reports for set jewelry, evaluating both the stones and the piece as a whole. This is particularly useful for engagement rings, bridal sets, and tennis bracelets.

Will I receive a physical IGI certificate with my Reverra Jewels purchase?

Yes. Every IGI-certified piece from Reverra Jewels arrives with its original IGI report. We also provide the report number so you can verify it yourself on igi.org at any time.

The Reverra Jewels Approach to IGI Certification

At Reverra Jewels, we've built our lab-grown collection around IGI certification for one simple reason: it's the most respected, most detailed, and most globally recognized standard for lab-grown diamonds available today.

When you buy a Reverra piece — whether it's a pair of solitaire studs, a tennis bracelet, an engagement ring, or a complete bridal set — you receive:

•        An IGI-certified diamond, fully documented on the 4Cs and growth method

•        A laser-inscribed report number, matching your certificate exactly

•        Handcrafted construction in 14K gold, platinum, or sterling silver, finished by artisans whose families have practiced fine jewelry-making for generations

•        Transparent pricing, because certification means you know exactly what you're paying for

•        Full traceability, from ethically sourced rough to finished piece

We're located at 15 W 47th Street in the New York Diamond District — the same few blocks where the American diamond trade has lived for over a century. If you'd like to see an IGI certificate in person, examine a laser inscription under magnification, or simply talk through the differences between two stones, our team is here. 

Final Word

An IGI certificate isn't a marketing detail. It's the document that turns a diamond from a stone into a known, verified, trustworthy gem. It's how you know what you're buying, what you're paying for, and what you're insuring.

For lab-grown diamonds especially, IGI is the standard the modern jewelry industry runs on — and it's the standard Reverra Jewels stands behind on every piece we make.