GIA Premium vs IGI 4Cs: pricing mixed lab-grown inventory

A parcel of lab-grown goods assembled over the past three years now carries incompatible kinds of paper: GIA reports with D–Z grades, GIA reports that say only Premium or Standard, and IGI reports with full 4Cs. Nothing about the stones changed — only the vocabulary used to describe them. That breaks side-by-side comparison at the point of sale, and it breaks valuation for any inventory system keyed on colour and clarity, because there is no field for "Premium".

What the GIA quality assessment actually certifies

GIA's D-to-Z laboratory-grown grading services ran until September 30, 2025. The GIA Laboratory-Grown Diamond Quality Assessment replaced them on October 1, 2025. It is not a renamed grading report. It collapses up to five separate judgements into one of two words.

Premium requires every one of the following: D colour, VVS clarity or better, Excellent polish, Excellent symmetry and, on round brilliants, an Excellent cut grade. Standard requires E–J colour, VS clarity, Very Good polish and Very Good symmetry (Good is accepted on fancy shapes), plus a Very Good cut grade on round brilliants. A stone that meets some Premium criteria and some Standard criteria is classified Standard — the lower rating governs. A stone that misses the Standard thresholds receives no assessment and is returned.

The service accepts loose, colourless to near-colourless stones from 0.15 ct upward. The fee is US$15 per carat with a US$15 minimum, so a 0.15 ct and a 0.50 ct stone cost the same to assess, while a 5.00 ct stone costs US$75. A stone that fails the Standard threshold still incurs a US$5 evaluation fee. Each assessed stone is laser inscribed on the girdle with "Laboratory-Grown" and its assessment number, and comes back with a printed document rather than the digital-only report the previous service issued. Fancy-colour and mounted laboratory-grown goods fall outside the assessment.

Which report formats now sit in dealer inventory

GIA's change was not the only one. HRD Antwerp announced on June 18, 2025 that from 2026 it would stop issuing quality certificates for loose synthetic diamonds intended for commercial use, while continuing to certify jewellery set with them. IGI went the other way and kept grading both natural and laboratory-grown stones on the 4Cs. Its volumes make that position hard to reverse: laboratory-grown stones were 54% of the diamonds IGI graded as of its mid-2025 financial update, and CEO Tehmasp Printer cited a 65% global share of laboratory-grown certification. The wider shift is covered in GIA vs IGI: what the 2025 grading shift means for your prices.

The practical consequence is that report format is now a sorting dimension in its own right, alongside shape, weight and colour. Four buckets behave differently.

Legacy GIA paper, issued before October 1, 2025, carries colour and clarity grades and is the only GIA format directly comparable with an IGI report. GIA has said these reports remain valid and has not offered to reissue them in the new format, so legacy paper stays in circulation on its original terms.

Current GIA paper carries no colour or clarity grade at all. Because the lower rating governs, a Standard stone can sit anywhere from D to J in colour and from VVS or better down to VS2 in clarity. Pricing a Standard stone off the rating alone hides that spread. One exception matters for cut-sensitive stock: an AGS Ideal addendum, with an ASET light map for stones that grade AGS0, is still available for qualifying rounds and fancy shapes at an extra fee. It has to be requested at submission, so it cannot be added to goods already assessed.

IGI paper carries full 4Cs. It is the only current format that maps cleanly onto grade-keyed price grids, which is a large part of why IGI dominates laboratory-grown grading volume.

Unpapered goods are the fourth bucket, and the one to watch. At current wholesale levels, a US$15 minimum fee is a material share of a small stone's value, and trade commentary expects price-led merchants to skip grading altogether. Stock in that bucket has no grade to price from and no inscription to verify against.

Repricing lab-grown stock when the grade language changes

The format question lands on a price base that has been falling for eight years. On Edahn Golan's LGD Wholesale Price Index, average laboratory-grown wholesale prices fell 13% year over year in Q2 2026, leaving the index roughly 96% below its July 2018 starting point, though the rate of decline keeps slowing. The movement is no longer uniform by size: 1.00 ct rounds rose 1% year over year while 1.50–1.99 ct fell 11% and 2.00 ct fell 20%. The June 2026 lab-grown price analysis covers the earlier leg of that curve.

Costs moved the other way. Some Chinese producers raised rough prices by at least 30%, and Diamond Foundry was reported to have raised prices by about 25% — a squeeze that argues against treating the long decline as automatic. On the demand side, US specialty retailers' laboratory-grown jewellery sales rose 24% in Q2 2026 on higher unit volume, according to Tenoris.bi, with retail price per unit holding in a narrow range for roughly eighteen months.

For stock already on the shelf, that points to three adjustments:

• Legacy GIA and IGI goods — keep pricing off the 4Cs, since the reference data supports it. Price a Diamond by Certificate resolves the comparable set from the report number.
• Current GIA Standard goods — price off an assumed mid-band position within E–J / VS, not off the word "Standard", and disclose the assumption to the buyer.
• GIA Premium goods — treat Premium as a narrow specification, not a synonym for "high grade". It is five simultaneous conditions, and failing any one produces a Standard stone.

The natural-diamond side shows how the substitution is being priced. On the Rapaport Trade Diamond Index, September 2026 asking prices rose 3.2% at 0.30 ct and 2.5% at 0.50 ct while 1.00 ct moved 0.3%. Smaller, lower-quality natural goods stayed under pressure from lab-grown competition, and those same goods were hard to move at the Hong Kong show. Report format is part of how that pressure reaches a price list.

Common questions about GIA Premium and Standard ratings

What do GIA Premium and Standard mean for lab-grown diamonds?

Premium requires D colour, VVS clarity or better, Excellent polish, Excellent symmetry and, on round brilliants, an Excellent cut grade — every applicable criterion, with no exceptions. Standard requires E–J colour, VS clarity, Very Good polish, Very Good symmetry (Good on fancy shapes) and a Very Good cut grade on round brilliants. A stone meeting a mix of Premium and Standard criteria is classified Standard. The system took effect October 1, 2025.

Does GIA still issue 4Cs grades for laboratory-grown diamonds?

No. GIA's D-to-Z laboratory-grown grading ran only until September 30, 2025, and new GIA laboratory-grown documents no longer print colour or clarity grades. Reports issued before that date remain valid. IGI continues to grade laboratory-grown diamonds on the full 4Cs; they accounted for 54% of the diamonds IGI graded as of its mid-2025 financial update.

What does a GIA laboratory-grown quality assessment cost?

US$15 per carat with a US$15 minimum, so a 0.50 ct stone costs US$15 and a 5.00 ct stone costs US$75. The minimum size is 0.15 ct and stones must be submitted loose. A stone that misses the Standard criteria receives no assessment and is returned, with a US$5 evaluation fee still payable.

Can a GIA Premium stone be compared directly to an IGI 4Cs stone?

Only in one direction. Premium implies D colour, VVS clarity or better and Excellent polish and symmetry, so an IGI report reading D / VVS / Excellent / Excellent describes a stone that would qualify. The reverse fails for Standard: because the lower rating governs, a Standard stone can sit anywhere from D to J in colour and from VVS or better down to VS2 in clarity, so the rating cannot be converted back into a single IGI-equivalent grade.

How far have laboratory-grown wholesale prices fallen?

Average laboratory-grown wholesale prices fell 13% year over year in Q2 2026 on Edahn Golan's LGD Wholesale Price Index, putting the index roughly 96% below its July 2018 level. The decline depends on size: 1.00 ct rounds gained 1% over the same period, while 2.00 ct stones lost 20%. Rough costs moved the opposite way, with some Chinese producers raising prices by at least 30%.

Treat report format as a pricing field, not a footnote

Mixed paper is now permanent: legacy GIA reports stay valid, IGI keeps grading on the 4Cs, and new GIA goods arrive with two words instead of two grades. If your inventory records only colour and clarity, every Standard stone either gets a guessed grade or falls out of the grid. Add report format as its own field, group stock by it — Organize Stones into Buckets handles that split — and reprice each group on the evidence it actually carries.

For how the issuing lab feeds into price more broadly, see Certification & Lab Grading and GIA certificate pricing.