Lab Grown Diamonds
Lab Diamond Treatments: What Buyers Must Disclose in 2026
Not every lab diamond is untreated. Some are annealed or color-enhanced. Here is what the certificate says, and what you must disclose.
The assumption that all lab grown diamonds are identical to mined diamond is mostly true - but not entirely. A share of lab diamond rough is treated after growth to improve color or clarity. The treatments are permanent and stable, but they must be disclosed, and the certificate will mention them. Buyers who skip the disclosure step build a compliance problem. Here is what the treatments are, how they show up on the certificate, and what you must tell your retail customer.
The common treatments
Lab diamond rough is grown in a chamber. Sometimes the resulting stone has a grayish or brownish tint that would grade as a lower color grade. Two post-growth treatments are common:
- HPHT annealing - the stone is reheated under high pressure to shift its color toward white. Common on CVD stones that started gray.
- Irradiation and heat - used to produce fancy colors (blue, green, yellow) that would not otherwise occur. These are sold explicitly as fancy-color treated stones.
Both treatments are permanent and do not wear off. They are not the same as the fracture-filling or clarity enhancement used on some mined stones. They are stable, standard industry practice, and they are disclosed on the grading report.
What the IGI report says
IGI reports for lab grown diamonds include a comment section. If the stone has been annealed or treated, the report will say so - usually phrased as 'HPHT treated' or 'color enhanced'. Untreated stones may say 'no indications of heat treatment' or may be silent. Buyers should read the comments section, not just the grade. A stone that grades DEF VS but carries a treatment note is a different product than an untreated DEF VS.
Untreated stones command a price premium, usually 10-20% over treated stones of the same grade. Whether that premium is worth it depends on your market. Most retail customers do not care about the treatment once it is explained, but they do care about being told. Disclosure is the issue, not the treatment itself.
Why disclosure matters legally
The FTC's Jewelry Guides require disclosure of treatments that affect value or durability. Selling a treated lab diamond as untreated is misrepresentation, and the importer who brands it is liable. The practical step is simple: if the IGI report says treated, say so on the hangtag and the product page. Customers who are told buy with confidence. Customers who find out later return.
How to buy around treatments
| Buyer type | Treatment stance | Price impact |
|---|---|---|
| Fine-jewelry / bridal | Specify untreated on PO | +10-20% per carat |
| Everyday jewelry | Treated fine, disclose on tag | Standard pricing |
| Fancy color | Treatment expected and disclosed | Premium for color |
When you place the parcel order, ask the supplier to state the treatment status on the parcel sheet. A reputable factory will tell you. A supplier that is vague on treatment status is a supplier you should not buy untreated stones from, because you cannot verify the claim.
Testing and verification
Modern diamond testers and lab reports separate treated from untreated stones, but a quick on-the-spot test at your end is wise on a new parcel. Send one or two stones to a local gemologist for verification if you are buying untreated. The cost is $30-$50 per stone and it confirms the supplier's claim. For treated stones sold as treated, the IGI report is the documentation.
Why untreated commands a premium
Untreated lab diamonds are rarer than treated ones, because a share of CVD rough needs annealing to reach a salable color. The untreated stones that do reach the market carry a 10-20% premium because they are closer to the 'natural growth' narrative that some customers want. Whether that premium is worth paying depends on your retail customer. A fine-jewelry boutique selling to knowledgeable buyers may want untreated stones. A fashion brand selling to customers who just want a white diamond at a fair price does not need to pay the premium. Specify on the PO, and the price moves accordingly.
The treatment question is ultimately a transparency question. The treatment itself is stable and permanent. The problem is when a treated stone is sold as untreated, which inflates the price and misleads the customer. Read the IGI comments, ask on the PO, and tell the retail customer what they are buying. Most customers, once they understand the treatment, are fine. The ones who are not are customers who would have felt misled later. Disclosure prevents the return, not the sale.
The treatment itself is not the problem. The undisclosed treatment is. Read the comments, ask on the PO, and tell the customer.
We disclose treatment status on every parcel sheet and provide the IGI report PDFs with each order. More on our lab diamond documentation is on the lab diamond program page. The treatment itself is not the problem. The undisclosed treatment is. Read the comments section, ask on the PO, and tell the customer.
Authoritative References
For buyers who need to verify the technical and regulatory basis of this guide, the following independent institutions publish authoritative reference data:
- GIA Gem Encyclopedia - independent grading and identification reference for natural and lab-grown gems.
- Wikipedia: Moissanite - peer-reviewed background on moissanite chemistry, optics and history.
