Buying and selling lab-grown diamonds: disclosure, pricing and placement
Lab-grown is a legitimate product with its own paperwork, its own price behaviour and its own risks. How the trade keeps it separate from mined goods.
A lab-grown diamond is a diamond. Same carbon, same crystal structure, same hardness, and in a finished ring the same look. That is not a marketing claim, it is why the category needs careful handling: nothing about the stone itself tells a customer, a staff member or a buyer at a stand where it came from.
The trade has largely stopped arguing about whether lab-grown belongs in a fine-jewelry case and moved on to the harder questions: how it is described on the ticket and the invoice, how it is priced when its replacement cost keeps falling, and where it sits so that it never gets confused with the natural goods in the next tray.
What the loupe and the tester cannot tell you
Separating lab-grown from mined is laboratory work, not bench work. A loupe will not do it, and neither will the common handheld diamond tester, which separates diamond from simulants and says nothing about origin. What exists for practical use is screening: most lab-grown diamonds contain no nitrogen, and the instruments built around that fact sort a parcel into stones that are certainly natural and stones that need referral. They condemn nothing, since a small share of natural diamonds share that chemistry; a referral means the stone goes to a laboratory, and for an individual stone a report settles it. Read the report type in the header before the grades: a lab-grown report is a different document from a natural one, and the way colour and clarity are described on it has changed more than once in recent years.
Say it in the words the rules use
Disclosure is a wording problem with a settled vocabulary. In the standards the trade works to, the word diamond on its own means a stone that came out of the ground, and a grown stone must carry a qualifier every time: laboratory-grown, laboratory-created, synthetic, or created by the named manufacturer. Abbreviations and inventions are the trap. Lab diamond, LGD and cultured on its own will not do, and words like real, genuine, natural and precious belong to the mined product. The other half of the rule is conspicuousness: the qualifier must be as prominent as the word diamond itself, wherever the stone is described. A disclosure made in conversation and left off the paperwork is not a disclosure; it is a dispute waiting for a resale or a claim.
Price it as a manufactured good
Mined diamond pricing rests on a finite quantity of material already out of the ground. Lab-grown pricing rests on factory capacity, and capacity has grown enormously while the cost per carat of growing has kept falling. Wholesale prices have dropped steeply and repeatedly, with nothing in the technology to suggest it will stop. Handling follows from that fact: own as little as possible for as short a time as possible, because deep owned inventory in a falling market is a slow loss hidden inside a healthy-looking margin percentage. Memo and made-to-order are the right structures. Price the category on its own terms rather than as a discount off a natural equivalent, and put value into design, metal and workmanship, which do not deflate.
Keep them apart, from the stand to the bench
Separation is physical and procedural, and it fails in ordinary moments rather than dramatic ones. A stone comes out for a comparison and goes back into the wrong tray. A repair take-in arrives with a customer's own centre of unknown origin. A parcel of melee is split across two jobs. None are dishonest acts, and each produces mixed stock and eventually an undisclosed sale.
- Separate cases, trays and stock numbers, and never a shared tray for a side-by-side comparison.
- Origin on the tag, the invoice, the appraisal and the memo in the full approved wording, not an abbreviation or an internal code.
- Separate memo bags and parcel papers, with origin written on the paper, not remembered.
- A written origin warranty from every supplier of melee and calibrated goods, naming the material in each parcel.
- A bench rule for customer-supplied stones: log what the customer says about origin, and screen anything going into a piece you will later describe.
- One script for the whole counter, so every member of staff discloses in the same words and the same order.
Melee is the real exposure. Nobody sends a quarter-point stone to a laboratory, undisclosed grown melee has turned up in supply chains more than once, and one mixed parcel reaches every piece it is set into. The answer is upstream: buy from suppliers who will warrant origin in writing per parcel, and screen what matters. Be careful what you promise, too: upgrade commitments and appraisals written at purchase price are where a falling replacement cost comes back to whoever signed them.
Nothing in a grown stone is fake. The only thing that can be false is the description attached to it.
Valumira's Antwerp show, 11 to 13 June 2027 at Antwerp Expo, puts rough, polished and lab-grown on separate floors, which is a convenience and a reminder: the separation only holds if you carry it home. Friday is the trade day there, as at every show in the series; Saturday and Sunday are open to the public. Walk that floor deliberately, with a brief and budget written for the category alone, and leave with invoices worded the way you intend to resell.