Lab Grown Diamonds
What Happened to GIA Lab Grown Diamond Grading in 2025?
The letter grades went away. Here is what replaced them, and what it means for a stone you are looking at today.
Written by the Mapple Gems workshop, Surat Β· Updated 18 August 2026
Short answer
From 1 October 2025, GIA stopped giving lab grown diamonds DβZ colour and FLβI3 clarity grades. It now issues a Laboratory-Grown Diamond Quality Assessment reading βPremiumβ or βStandardβ β or nothing, if the stone clears neither. Reports issued before that date keep their letter grades and are still valid. IGI and GCAL still issue full 4C detail, and IGI grades most lab grown production.
If you have been shopping for a lab grown diamond and found that two reports for similar stones look nothing alike, this is why. The most recognised name in diamond grading changed how it describes lab grown stones, and the change is more significant than a formatting tweak.
What actually changed
Before October 2025, a GIA report for a lab grown diamond looked much like one for a mined diamond: a colour letter from D to Z, a clarity grade from Flawless to I3, a cut grade for rounds, and the measurements.
Since then, GIA places a lab grown stone into one of two descriptive bands instead.
| Assessment | Roughly what it covers |
|---|---|
| Premium | Top colour range, VVS clarity and better, excellent polish and symmetry, and for round brilliants, excellent cut. |
| Standard | A wider colour band and VS-level clarity. |
| Neither | A stone that does not clear the Standard threshold receives no assessment. |
Check the current GIA description directly before relying on the exact boundaries; the bands are defined by GIA, not by us.
Why GIA did it
The stated reasoning is that lab grown production has become so consistent that the traditional scales stopped separating stones usefully. When an overwhelming share of output lands in a narrow band at the top of both scales, a letter grade communicates less than it appears to β and it invites a comparison with mined diamonds, where rarity across the range is what the scale was built to measure.
Whether you find that persuasive or not, the practical effect is the same: a new GIA lab grown report gives you less to compare with.
What this means when you are actually shopping. Two stones can both read βPremiumβ and still differ in ways you would have seen instantly on the old scale. If you are choosing between specific stones and you want to compare them properly, look for an IGI or GCAL report, which still carry the granular 4Cs. And if a seller shows you an older GIA report with letter grades, that report has not been invalidated β it just predates the change.
Does an older GIA report still count?
Yes. A GIA report issued before 1 October 2025 keeps its DβZ colour and FLβI3 clarity grades, and you can read it exactly as you always did. Nothing about the stone changed; only the way new reports are written did.
This does create one thing to watch for. A stone with a pre-change GIA report is not automatically better or worse than one assessed under the new system β they are simply described differently. Do not let a seller imply that letter grades on an older report make a stone superior to a βPremiumβ one.
Which lab should you look for now?
- IGI β grades the majority of lab grown production and reports full 4C detail, including colour letter, clarity grade, and cut grade for rounds. For most buyers this is now the most useful report to have.
- GCAL β also issues full detail, and adds light-performance measurement, which some buyers value.
- GIA (post-October 2025) β a Premium or Standard assessment. Highly credible, less granular.
- An in-house or unnamed βcertificateβ β not an independent report. Treat it as marketing.
Two things this change does not affect
It does not change what a lab grown diamond is. A lab grown diamond remains chemically, physically and optically diamond regardless of who graded it or how.
And it does not change the price picture. Lab grown prices fell steeply from 2020 to 2024 and have since flattened near production cost. The grading change is about description, not value β and it is not a reason for anyone to charge you more.
Keep reading
Frequently asked questions
Does GIA still grade lab grown diamonds?
Yes, but differently. Since 1 October 2025 GIA issues a Laboratory-Grown Diamond Quality Assessment describing a stone as Premium or Standard, rather than assigning DβZ colour and FLβI3 clarity grades. A stone that meets neither band receives no assessment.
What is the difference between GIA Premium and Standard?
Premium covers the top colour range with VVS clarity or better and excellent polish and symmetry, plus excellent cut for round brilliants. Standard covers a wider colour band at VS-level clarity. Because each band spans a range, two stones sharing an assessment can still look different from one another.
Is my older GIA lab grown report still valid?
Yes. Reports issued before 1 October 2025 keep their letter grades and remain valid. The stone has not changed; only the format of newly issued reports has. An older report is not evidence of a better stone, and a newer one is not evidence of a worse one.
Should I buy a lab grown diamond graded by IGI instead?
If you want to compare specific stones against each other, yes β IGI still reports the full 4Cs and grades most lab grown production, and GCAL does the same. If you simply want independent confirmation from a highly credible lab, a GIA assessment is fine; it just tells you less.
Our lab grown stones are IGI certified.
Full 4C detail on every stone, so you can compare properly rather than take our word for it.
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