Buying Guides
CVD vs HPHT Lab Grown Diamonds: What Buyers Need to Know
CVD and HPHT produce diamonds with the same chemistry but different growth signatures, cost profiles and typical quality ranges. Here is what matters commercially.
Both CVD and HPHT produce diamonds that are chemically identical to mined stones. The differences that matter to a wholesale buyer are growth time, typical color and clarity ranges, cost, and how the production method is disclosed on certificates.
The two methods compared
| Factor | CVD (Chemical Vapor Deposition) | HPHT (High Pressure High Temperature) |
|---|---|---|
| How it grows | Carbon plasma deposits onto a diamond seed plate | Carbon dissolves in molten metal flux and crystallises |
| Typical growth time | 3–6 weeks | 1–3 weeks |
| Common color range | D–G, often needs post-growth treatment | F–J, frequently near-colorless without treatment |
| Typical clarity | VVS–VS common | VS–SI more common |
| Larger sizes | Well suited to 1 ct+ | Better suited to melee and mid sizes |
| Cost profile | Scales well at volume | Energy intensive, costlier at large sizes |
| Certificate disclosure | Method stated on IGI/GIA report | Method stated on IGI/GIA report |
Why the method matters to you
- Color and clarity distributions differ, so your specification sheet should name the method you are buying.
- Price differs at the same grade — do not accept a mixed-method parcel quoted as one grade without disclosure.
- Some markets and retailers prefer one method, particularly where the growth process is part of the customer story.
- Method should be stated on the certificate; if it is not, ask for it in writing.
Post-growth treatment
Some CVD stones are annealed to improve color. This is accepted industry practice and should be disclosed on the report. Ask whether the stones you are buying have been treated, and require that the answer be written into your approval sheet.
What to write into your purchase specification
| Item | Recommended specification |
|---|---|
| Method | CVD or HPHT — state explicitly, no mixing |
| Color | D–F for premium lines, G–J for value lines |
| Clarity | VS1–VS2 for retail consistency; VVS on request |
| Treatment | Disclosed, or "none" in writing |
| Certification | IGI or GIA above 0.50 ct, inscribed |
| Tolerance | Color ±1 grade, clarity ±1 grade against approved master |
Sourcing both from one supplier
Buying both methods from a single factory keeps your master sample file, packing standard and shipping schedule consistent. We supply both CVD and HPHT, and we state the method on every specification sheet and certificate so your downstream documentation is never ambiguous.
What to put in your purchase specification
Before you place a wholesale order, write the specification down and make the factory confirm it in writing. Every dispute we see between a buyer and a supplier traces back to a vague or missing specification sheet. The following items are the ones that actually cause problems when they are left open:
| Item | What to state |
|---|---|
| Stone grade | Colour and clarity range, plus the tolerance you will accept against the approved master sample (±1 grade is standard) |
| Metal and purity | Exact karat or silver fineness, alloy type, and whether white gold is nickel-free |
| Plating | Type (rhodium, 18K gold) and thickness in microns — a thin flash plating wears through in months |
| Dimensions | Band width, stone measurement, chain length, and the weight tolerance per piece |
| Setting method | Prong, bezel, channel or pavé — this single choice can double labour cost |
| Packing | Poly bag, box, pouch, tag, barcode label, and how many pieces per carton |
| Documents | Which certificates, and whether you need a material declaration or assay report |
MOQ, lead time and payment terms
Our standard terms across the catalogue are straightforward, and they are the same terms we quote in writing rather than adjusting per enquiry:
- MOQ — 10 pieces per design for stock specifications, 50 pieces for mixed-design lots. Custom development starts from 30 pieces per style in 925 silver and 10 pieces in gold.
- Tiered pricing — list price to 49 pieces, about 8% off from 50 pieces, about 14% off from 200 pieces, and negotiated pricing above 500 pieces with reserved production capacity.
- Lead time — 7–15 days for stock designs, 10–20 days for custom or certified production runs. Add 3–7 days for express transit to Europe and North America.
- Payment — 30% deposit with the balance before shipment, by T/T, PayPal, Western Union or Alibaba Trade Assurance.
- Samples — single samples ship at list price and the cost is credited against your first order above 200 pieces.
- Quality guarantee — 30-day return window on stock items, and a written remanufacture-or-credit commitment if a parcel falls outside the approved tolerances.
Quality control: what happens before your parcel leaves
Buyers who have been burned before usually want to know exactly what inspection was performed. This is our standard sequence on every wholesale order, whether it is 20 pieces or 2,000:
- Incoming stone grading. Every parcel is checked for colour, clarity and measurement against the order sheet before it enters the setting line. Rejected stones are pulled, not downgraded and used anyway.
- In-process inspection. Setters check prong security, stone alignment and surface finish at each station rather than at the end of the line.
- Final QC under 10× magnification. Polish, plating thickness, clasp and hinge function, and hallmark accuracy are verified piece by piece.
- Cleaning, photographing, packing. Pieces are cleaned, photographed against your PO number, and packed in individual poly bags inside export cartons.
- Document preparation. Commercial invoice, packing list, certificate copies and — where required — a material declaration stating that the stones are laboratory-grown.
You receive the photographs and the packing list before the parcel ships, so you can flag anything before it leaves rather than after it arrives.
Frequently asked questions
Can I mix metals and stone grades in one order?
Yes. You can combine 925 sterling silver, 10K, 14K and 18K gold in the same production run, and specify different colour and clarity grades per line. Every combination is confirmed on a single approval sheet before production starts, so there is no ambiguity about which line is which.
How consistent is grading across repeat orders?
Repeat orders are graded against the master sample kept on file under your account, which is why buyers who reorder regularly see far less variation than buyers who switch suppliers each season. Tolerances are written into the approval sheet, so a reorder cannot drift without your written agreement.
Do you provide photography for my online store?
Every catalogued design has front, three-quarter and macro imagery in sRGB at print resolution, named to match the SKU so the assets map straight into your product database. For orders above 200 pieces we photograph your private-label version at no additional cost.
What happens if the goods do not match the sample?
Send photographs and the SKU list within 14 days of delivery. If the deviation exceeds the tolerances on your approval sheet, we remake the affected pieces or issue a credit — this is covered by our written quality guarantee and applies to every order, not only the first one.
Related wholesale collections
- Loose Lab Grown Diamonds Wholesale — 87 ready designs, MOQ from 10 pcs.
- Lab Grown Diamond Supplier — 67 ready designs, MOQ from 10 pcs.
- Lab Grown Diamond Rings — 39 ready designs, MOQ from 10 pcs.
Related Articles
- 10K vs 14K vs 18K Gold: A Manufacturing Guide for Buyers
- Lab Grown Diamond Traceability: What Buyers Should Demand
Authoritative References
For buyers who need to verify the technical and regulatory basis of this guide, the following independent institutions publish authoritative reference data:
- ISO 9001 Quality Management - the international standard for consistent production quality.
- Wikipedia: Jewellery - manufacturing processes, materials and global trade background.
