When a customer asks whether a lab-grown diamond is “certified”, they usually mean one thing: is there an independent grading report? For retailers, the more useful questions are which lab issued the report, what the report actually says and whether it matches the piece in the case. This guide compares the lab-grown diamond reports retailers see most often, IGI and GIA, and lists what to ask your supplier for.
Grading reports, not certificates
A grading report records a laboratory's findings; it is not a price appraisal or a guarantee of future value. A report records the lab's assessment of a stone at the time it was examined: its identity as a laboratory-grown diamond, its measurements and, depending on the lab and report type, its quality characteristics. Reports are valuable because they are independent, but they describe the stone, not the finished piece, and they are only useful if the stone in the jewelry is the stone on the report.
IGI lab-grown diamond reports
The International Gemological Institute (IGI) is a major provider of laboratory-grown diamond reports. Its April 2025 investor presentation reported approximately 65% global share by number of laboratory-grown diamond certifications in 2023, citing an August 2024 Redseer industry report; that is not a current U.S.-specific market-share figure. IGI lab-grown reports typically grade the stone on the familiar 4Cs scale, color, clarity, cut grade where provided by the applicable report service, and carat weight, alongside measurements and a clear statement that the diamond is laboratory-grown. Many IGI lab-grown reports also note the growth method (CVD or HPHT) and any post-growth treatment, and many stones are laser-inscribed on the girdle. Check the report's inscription field and verify the actual inscription on the stone; do not assume every report uses identical wording.
Because IGI uses the same grading language customers already know from natural diamonds, IGI reports are easy to explain at the counter and easy to compare across stones.
GIA lab-grown diamond reports
The Gemological Institute of America (GIA) is the best-known name in natural diamond grading. Effective October 1, 2025, GIA replaced its previous D-to-Z laboratory-grown diamond reporting service with the GIA Laboratory-Grown Diamond Quality Assessment. For eligible loose colorless-to-near-colorless laboratory-grown diamonds weighing at least 0.15 carats, it assigns an overall “Premium” or “Standard” assessment based on quality criteria, rather than issuing the natural-diamond-style grading report previously used. Stones below the minimum Standard criteria do not receive this assessment. GIA offers separate report services for laboratory-grown colored diamonds, so check the stone, report type and issue date before comparing documents.
For retailers, the practical point is simple: a GIA lab-grown report and an IGI lab-grown report may not describe quality in the same way, so the two should not be compared grade for grade. Always check the current report format on the lab's own website before you train staff or print signage.
Which report should you ask for?
There is no single right answer, but most retailers weigh four things:
- Customer familiarity: customers who have shopped lab-grown online often expect 4Cs grades, which IGI reports provide.
- Consistency across your case: using one lab for most of your lab-grown inventory makes comparisons and staff training easier.
- Stone size: grading reports are most common on center stones and larger single stones. Small stones in tennis bracelets and pavé are often not individually reported.
- Cost: reports add cost per stone, which matters more on smaller pieces.
What to ask your supplier
- Which styles and stone sizes come with a grading report, and from which lab?
- Is the report number laser-inscribed on the stone, and does the inscription identify it as lab-grown?
- Does the report state the growth method and any post-growth treatment?
- For pieces without an individual report, how are stone quality and total carat weight described on the invoice?
- Can reports be supplied digitally so you can link them in your online listings?
- Is every lab-grown piece identified as lab-grown on the invoice and packing documents?
Ask Nivelle to confirm the specifications, documentation and report availability for your selected style before ordering. You can browse styles in our lab-grown diamond jewelry collection.
How to explain reports to customers
Keep it short and honest. A grading report is an independent lab's description of the stone. It confirms that the diamond is laboratory-grown and records its measurements and characteristics. It is not an appraisal and does not set a price. For tennis bracelets and pavé pieces, explain that small stones are often not individually reported, and state the total carat weight and quality range on the receipt.
Whatever the report says, disclosure comes first: every lab-grown piece should be described as lab-grown on tags, receipts and listings. Learn more about our wholesale lab-grown diamond jewelry program.
Keeping reports organized
Treat grading reports as part of the product. Store a digital copy of each report with the SKU in your point-of-sale or inventory system, so any salesperson can pull it up at the counter. When a graded piece sells, give the customer the report or a copy with the receipt, and note the report number on the receipt itself. For online listings, linking the report or showing the report number builds trust with buyers who cannot see the piece in person. And when you reorder a style, confirm that new stones come with the same type of report, so your case stays consistent from one delivery to the next.
Frequently asked questions
Is an IGI report better than a GIA report for lab-grown?
Neither is simply better. They describe lab-grown diamonds differently. IGI reports use 4Cs grades that customers recognize, while GIA now issues an overall Premium or Standard assessment for eligible stones. Choose the format that fits your customers and use it consistently.
Do lab-grown tennis bracelets come with grading reports?
Small stones are often not individually reported. Ask the supplier which stones are covered by any report and how total carat weight and quality ranges are documented.
How can I tell a stone matches its report?
Check the report's inscription field, verify the actual inscription on the girdle under magnification, and compare the measurements and carat weight.
Does a report prove a diamond is lab-grown?
A report from a recognized lab identifies the stone as laboratory-grown. That identification should always be repeated on your tags, receipts and listings.
Where can I see wholesale lab-grown styles?
Browse our wholesale lab-grown rings and lab-grown earrings, or apply for a trade account on our contact page.
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