Lab-grown diamonds are real diamonds. They are not simulants (that is what moissanite and cubic zirconia are). Chemically, optically and physically, a lab-grown diamond is indistinguishable from one pulled out of the ground. The difference is how it got there.
How they are made
Two industrial processes dominate:
- HPHT (high pressure, high temperature) — a small diamond "seed" is placed in a chamber with carbon and subjected to pressures and temperatures similar to those deep in the earth. The diamond grows over days.
- CVD (chemical vapour deposition) — a diamond seed is lowered into a chamber filled with carbon-rich gas. The gas is plasma-activated and carbon atom-by-atom deposits onto the seed. Slower, but more precise for fancy colours.
Grading and certificates
Reputable labs (GIA, IGI, GCAL) grade lab-grown diamonds on the exact same 4C scale as mined stones. A "G VS1 Excellent" lab-grown diamond is graded the same way as a mined one. The certificate will usually say "lab-grown" or "synthetic" on it — that is required, not a hidden detail.
Price
Lab-grown diamonds typically cost 40–60% less than a comparable mined diamond at retail. The price gap has widened over the last five years as production capacity has scaled. For a 1ct solitaire, the difference in the UK is often several thousand pounds.
Resale value
This is the catch. Mined diamonds already hold resale value poorly. Lab-grown diamonds hold it even less, because supply keeps increasing. If you are buying an engagement ring, buy it to wear, not as an asset.
Lab-grown vs moissanite
Both are ethical, lab-grown choices. A lab-grown diamond is still a diamond — it is harder (10 vs 9.25 on Mohs), has less rainbow "fire", and will cost more than a moissanite ring but less than a mined diamond. Our moissanite vs diamond guide walks through the trade-offs.