Ask a jeweller what changed about lab grown diamonds this year and the honest answer is not the stones. It is the paperwork. IGI vs GIA used to be a footnote on a receipt. It is now the difference between getting a familiar 4Cs grade and getting no grade at all.

In 2025, GIA stopped applying its natural-diamond color and clarity scales to laboratory-grown diamonds and replaced them with a two-tier descriptive system. IGI kept grading lab grown stones the way buyers already understood. That single divergence reshaped what a certificate means, what it is worth paying for, and which numbers on the page actually protect you. Here is the current state of play, in plain language.

IGI vs GIA: What Changed in 2025

GIA no longer issues 4Cs color and clarity grades for lab grown diamonds, while IGI still does, which is why almost every lab grown diamond on the market today arrives with an IGI report. GIA announced the shift in June 2025 and launched the replacement service, the GIA Laboratory-Grown Diamond Quality Assessment, on October 1 of that year. The reasoning was straightforward. As Tom Moses, GIA's Executive Vice President and Chief Laboratory and Research Officer, put it in GIA's announcement, "More than 95% of laboratory-grown diamonds entering the market fall into a very narrow range of color and clarity."

When almost everything is D to F and VVS to VS, a 23-point scale stops sorting anything. GIA's answer was to sort lab grown stones into just two categories, premium and standard, with anything below the standard minimums receiving no GIA assessment at all. GIA president and CEO Pritesh Patel was blunt about the logic: the institute "will no longer use the nomenclature created for natural diamonds."

IGI took the opposite road. It continues to issue full 4Cs reports for lab grown diamonds, which is one reason it now dominates the category. IGI's managing director and CEO Tehmasp Printer has put the company's position at "a 33% global market share in diamond certification and 65% in lab-grown diamonds," as reported by Rapaport. For context on scale, IGI operated 29 laboratories across 10 countries at the time Blackstone acquired the business, and it has been certifying lab grown diamonds since 2005.

How to Read an IGI Lab Grown Diamond Report

An IGI lab grown diamond report is a measurement sheet, not a quality endorsement, and five fields on it carry almost all the useful information. Read them in this order and you will know in under a minute whether a stone is honestly priced.

• Report number and laser inscription. The number on the page must match the number inscribed on the girdle. If a seller cannot show you both, nothing else on the report matters.
• Growth method. CVD or HPHT. Neither is better, but the report should say which, because it tells you the stone was identified rather than assumed.
• Color and clarity. For lab grown, the honest range sits around D to G and VVS2 to VS2. Paying a premium above that band buys a word on paper, not visible difference.
• Cut, polish and symmetry. This is where money actually shows. Excellent across all three is worth more to the eye than one color grade.
• Post-growth treatment. The report should state whether color was altered after growth. Untreated is the cleaner buy.

If you want the longer version of the two fields buyers overthink most, our guides to VS1 versus VS2 clarity and D, G and H color grades walk through where the visible thresholds sit.

IGI Report vs GIA Quality Assessment: Side by Side

The two documents now answer different questions, so comparing them like-for-like is the wrong instinct. An IGI report tells you where a stone sits on the traditional scale. A GIA assessment tells you whether a stone clears a bar.

Neither document says anything about how a stone was set, finished or secured, which is where a lot of real-world value and failure actually lives. That is a jeweller's responsibility, not a lab's.

What IGI vs GIA Means for What You Buy

For a finished piece, the certificate matters less than the consistency of the stones and the quality of the setting, because a lab report grades one diamond while a bracelet holds dozens. Every lab grown diamond Roomy's sets is IGI certified and Roomy's certified, and the pieces below show how that plays out across price bands in solid 10kt, 14kt and 18kt gold.

• Eclat Emerald Diamond Tennis Bracelet (from $500). Emerald cuts are the most unforgiving shape to match, which makes consistency the whole point.
• Opale Round Diamond Tennis Bracelet (from $550). A 0.63 CTW line, sized for daily wear rather than display.
• Celeste Round Diamond Tennis Bracelet (from $1,700). At 0.55 CTW per stone scale, it reads as light rather than loud.
• Prestige Round Diamond Tennis Bracelet (from $5,100). High-carat, where matched cut grades across the line are doing the heavy lifting.
• Oval Diamond Solitaire Pendant (from $2,000). One stone, nowhere to hide, which is exactly when a report earns its keep.
• Starlight Portal Diamond Stud Earrings (from $1,500). Pear diamonds set around an open centre, matched as a pair.

The practical takeaway is simple. Ask for the report, check the inscription, then spend the rest of your attention on cut quality and craft. If you are shopping for the ring rather than the paperwork, our guide to engagement ring trends in 2026 covers what couples are actually choosing this year.

Frequently Asked Questions