A lab grown diamond is a diamond. It has the same chemical composition, crystal structure, hardness and optical properties as a mined diamond — it simply grew in a reactor rather than in the earth. For wholesale buyers, the questions that matter are growth method, certification economics and price direction.
How they are made
CVD (chemical vapour deposition) grows diamond from a carbon-rich plasma onto a thin diamond seed plate. It scales well, produces mostly colourless material in the commercially valuable D–F range, and dominates volume supply.
HPHT (high pressure high temperature) reproduces natural diamond-forming conditions, dissolving carbon in a metal flux so it crystallises on a seed. It yields excellent clarity but lower throughput, and is generally used for larger, higher-value stones.
CVD vs HPHT for buyers
| Factor | CVD | HPHT |
|---|---|---|
| Typical colour | D–F, occasional brown tint if unsorted | D–F, E–F typical |
| Typical clarity | VS–SI common | VVS–VS common |
| Post-growth treatment | Common for colour improvement (must be disclosed) | Less common |
| Relative price | Lower at volume | Higher, especially above 1 ct |
| Best commercial use | Melee, 0.3–2 ct rounds, fashion lines | Certified centre stones, bridal |
Reading an IGI report
- Report number — verifiable in the laboratory's online lookup, and inscribed on the stone's girdle.
- Measurements — millimetres, not just carat weight. Always verify with callipers.
- Colour and clarity grades — assigned by the laboratory, not by the seller.
- Polish and symmetry — the cut-quality indicators that most affect appearance.
- Growth method and treatment status — legally relevant in several markets and often omitted in cheap quotations.
- Fluorescence — blue fluorescence can affect appearance in some lighting.
What moves the wholesale price
- Size. Price per carat rises steeply above 1.5 ct because fewer large roughs survive cutting.
- Colour and clarity. Moving from G/VS to D/VVS at the same size can add 40–80%.
- Certification. A certified 1 ct stone can carry a 15–25% premium over an uncertified equivalent.
- Growth method. HPHT typically carries a modest premium, most visibly above 1 ct.
- Market timing. Because supply is manufactured, prices have historically drifted down rather than up — structure agreements with a price-review clause.
Disclosure and market rules
Lab grown diamonds must be disclosed as lab grown in most consumer markets, and the terminology is regulated in several. Your supplier's invoice is your evidence trail: it should name the goods accurately, state the growth method where known, and list certificate numbers per line. Buyers who cannot produce that paper are exposed at retail.
Specification template
Stone: lab grown diamond, CVD, 1.20–1.30 ct, F colour, VS1 clarity, round brilliant, excellent polish and symmetry, IGI certified with girdle inscription; metal: 14K white gold, 3.2 g ±5%; setting: six-prong; MOQ 10 pcs; lead time 12–18 days.
Parcel buying for lab grown diamonds
Loose stones are often bought as parcels — groups sold together at a blended price per carat. Always request the breakdown by size band, colour and clarity with counts per band, then calculate the effective price of the stones you can actually set. A parcel that looks cheap per carat may contain a large share of grades you cannot use, which changes its true cost. For matched sets — three-stone rings, earring pairs, bracelet runs — sort by millimetre size first, then colour on white paper in daylight, then clarity under magnification.
Matching a reorder months later
- Retain a physical reference stone for every grade you buy, labelled and stored together.
- Record the growth method and colour range on your own purchase order, not just the certificate number.
- Confirm with your supplier that the same stone source will be used for the reorder.
- Buy sufficient quantity for the season rather than topping up monthly, so a single production batch covers the run.
Documentation for retail
If your customers ask for provenance, the documents you can hand over are the certificate, the commercial invoice naming the goods as lab grown, and any material declaration for the metal. Buyers in markets with disclosure rules should ensure the invoice states the growth method, and should keep certificate copies on file for at least the life of the retail sale. Your supplier's paperwork is your evidence trail.