ELMONAS / EDUCATION
CVD vs HPHT: how lab-grown diamonds are made
The short answer
CVD and HPHT are the two methods used to grow lab-grown diamonds, and both grow real diamond.
What is the short answer?
CVD and HPHT are the two methods used to grow lab-grown diamonds, and both grow real diamond. HPHT grows diamond around a seed inside a metal capsule at very high pressure and temperature; CVD grows diamond layer by layer from a carbon gas at near-vacuum pressure.
Neither method is a treatment or an imitation. The result of both is a diamond with the same carbon crystal structure as a mined diamond, which a laboratory can grade in the usual way.
How does HPHT growth work?
HPHT (high-pressure, high-temperature) recreates key conditions of natural diamond formation. A capsule holding a carbon source, a metal mixture and a small diamond seed is heated to about 1300 to 1600 degrees Celsius under pressures of 5 to 6 GPa, conditions comparable to a depth of roughly 150 to 190 km inside the earth.
Carbon dissolves in the metal and crystallizes on the seed. The size of the finished crystal depends on the growth time and the volume of the capsule. The same press technology can also be used to treat diamond color, which grading reports disclose.
How does CVD growth work?
CVD (chemical vapor deposition) grows diamond at near-vacuum pressure. Inside a chamber, a carbon-containing gas is energized, typically by microwaves, into a glowing plasma, and carbon deposits onto flat diamond seed plates at about 700 to 1200 degrees Celsius.
Growth proceeds layer by layer, each layer repeating the crystal structure beneath it, building a block of diamond. The final size depends on the size of the seeds and the growth time.
How do the two methods compare?
| HPHT | CVD | |
|---|---|---|
| Pressure | 5 to 6 GPa (very high) | Near vacuum |
| Temperature | About 1300 to 1600 °C | About 700 to 1200 °C |
| Carbon source | Carbon dissolved in a metal mixture | Carbon-containing gas |
| Growth starts from | A diamond seed inside a capsule | Flat diamond seed plates |
| Growth pattern | Crystal grows around the seed | Layer-by-layer growth |
| First production | 1950s, General Electric and others | 1952, Union Carbide |
| Gem-quality at scale | Mid-1980s: commercial quantities of gem-quality crystals | 2000s: gem-quality diamonds created by CVD |
Dates are from GIA's published history of laboratory-grown diamonds: https://4cs.gia.edu/en-us/simulants-moissanite-and-lab-grown-diamonds/
Can a laboratory tell which method grew a stone?
Yes. GIA states that it can determine whether a diamond was grown by HPHT or CVD using spectroscopy and other testing methods, and IGI states that, on request, the growth process used and the presence of treatments are noted in the comments section of its lab-grown diamond report.
The growth method does not change the fact that the stone is diamond. Reports also disclose any evidence of post-growth treatment.
Does the growth method matter to a buyer?
For wearing and grading, no: both methods produce diamond, graded by the same laboratories on the same properties. Where the method matters to you, for example for a specific trade requirement, ask for it with your enquiry and it will be confirmed with the stone's report.
For the wholesale buyer's view, including how to choose by the finished stone, see CVD vs HPHT for wholesale buyers.
Where can I see lab-grown diamonds?
Sources
- GIA 4Cs, Simulants, Moissanite and Lab-Grown Diamonds (growth conditions, history, identification): https://4cs.gia.edu/en-us/simulants-moissanite-and-lab-grown-diamonds/
- IGI, Laboratory Grown Diamond Report (growth process noted in report comments): https://www.igi.org/reports/lab-grown-diamond-report/
Last reviewed: 18 October 2026
Discuss your requirement with Elmonas. We reply on WhatsApp during Surat business hours (IST).
