CaratWire
Loose round-brilliant-cut diamonds beside a chrome jeweler's loupe on a white surface, evoking professional diamond grading
Photo by Gemsparkdiamonds via Wikimedia Commons

IGI vs GIA Lab-Grown Grading: What the 2025 Report Format Change Means

6/4/2026 · 5 min read

This is a spoke of our hub article Lab-Grown vs Natural Diamonds: what the 2026 price collapse actually means. If you're trying to decide between an IGI lab-grown report and a GIA lab-grown report, the format change GIA made on October 1, 2025 is the only fact that actually matters.

What GIA changed in October 2025

Before October 2025, GIA graded lab-grown diamonds on the same 4Cs continuum it uses for naturals — full color (D–Z), full clarity (FL through I3), full cut grade. The October 2025 update collapsed that into two tiers:

  • Premium — D color, VVS or better clarity, Excellent polish and symmetry; Excellent cut on rounds.
  • Standard — E–J color, VS or better clarity, Very Good polish and symmetry; Very Good cut on rounds.

Stones below Standard get no GIA report at all. The granular grade is gone. A GIA "Premium" lab-grown could be a true D/VVS1 or it could be an F/VVS2 — the report no longer tells you which.

Why IGI still matters more for lab-grown pricing

IGI grades an estimated 65–70%+ of all certified lab-grown diamonds globally and still prints the full 4Cs on every report. Because the major US lab-grown retail channels — including Signet brands — built their inventory and price books around IGI paper, the wholesale market continues to quote lab-grown off IGI grades.

That means the lab-grown price you actually see at retail and on RapNet is benchmarked to an IGI letter and number. A GIA "Premium" stamp gives you a floor but not a market-clearing grade. For a lab-grown center stone where you want to negotiate dollars, an IGI report is the instrument the market reads.

How to price the report difference

Three rules of thumb, drawn from the hub piece on lab-grown resale reality:

  1. For a lab-grown stone with an IGI report, price off the printed grade — D/VVS1, E/VS1, etc. — against current per-carat lab-grown comps. The grade is the spec sheet.
  2. For a lab-grown stone with only a GIA Quality Assessment, treat "Premium" as a floor (assume the bottom of the Premium bucket, not the top) and refuse to pay a brand premium for the GIA logo. Lab-grown prices fall every quarter; report prestige doesn't arrest that.
  3. Never put an IGI grade and a GIA grade on the same comparison line. They're measuring different things now. IGI prints a number; GIA prints a tier.

For background on how IGI and GIA differ on naturals — where IGI tends to grade one increment looser on color and clarity — see our full GIA vs IGI comparison. The lab-grown story is structurally different from that one.

What to ask the seller

"Is there an IGI report with the printed 4Cs, or only a GIA Quality Assessment? If GIA-only, I'm pricing this as the bottom of the Premium tier."

A seller asking GIA Premium money on a stone with no IGI cross-reference is asking you to pay for a logo. The reactor that grew the diamond — and the per-carat math from the hub article — does not care which lab graded it.

Outside reference

For an industry-side perspective on certification and the broader diamond trade, the Antwerp-based dealer Ajediam publishes detailed notes on lab certification that are useful context if you're sourcing internationally. The certification choice they recommend mirrors what the per-carat math forces: IGI for lab-grown specs, GIA for naturals you'd ever resell.

The one-line summary

For a lab-grown diamond in 2026, ask for IGI. A GIA "Premium" stamp is a quality floor, not a negotiating instrument, and you should never pay a GIA-paper premium on a stone the market prices off IGI grades.