CVD vs HPHT Lab-Grown Diamonds: What's the Difference?
The two processes used to grow diamonds in a lab produce real diamonds by different routes — and the difference shows up in typical colour, clarity and price.
Every lab-grown diamond on the market today is produced by one of two processes — CVD or HPHT. Both produce a real diamond, chemically and optically identical to a natural stone (see our lab-grown vs natural overview), but the two routes get there differently, and that difference shows up in what you're actually buying.
HPHT: replicating the pressure
High-Pressure High-Temperature growth subjects a small diamond seed to roughly 5-6 gigapascals of pressure and around 1,500°C, dissolving carbon source material in a molten metal flux so it crystallises onto the seed — a lab-scale replica of the pressure and heat that forms natural diamond underground. HPHT diamonds tend to grow into a cuboctahedron shape and, because the process is exposed to nitrogen, are more prone to a yellowish tint and can carry small dark, metallic flux inclusions.
CVD: building up from a gas
Chemical Vapour Deposition instead fills a vacuum chamber with carbon-rich gas that's ionised into a plasma, causing carbon atoms to deposit layer by layer onto a flat diamond seed. It runs at lower pressure and requires less upfront equipment investment than HPHT, which is a large part of why CVD now accounts for the majority of global lab-grown diamond production. CVD stones tend to grow with fewer inclusions and better starting clarity, but the layered growth often leaves a brownish tint that most CVD producers correct with a secondary HPHT annealing step after growth — itself a disclosable treatment.
Does the process matter to a buyer?
Not for authenticity — both are real diamond, and a report will confirm origin either way (see our certification guide). It matters more indirectly: CVD's clarity advantage and lower production cost are a big part of why lab-grown supply has scaled so fast and prices have fallen so far (see do lab-grown diamonds hold their value). A good report will note which process grew the stone and whether it was subsequently treated — ask to see that line if it isn't obvious on the report you're given.
Related reading
- Lab-grown vs natural diamonds: what buyers need to know
- Lab-grown diamond certification: what to check
- Can jewellers tell if a diamond is lab-grown?
Sources: growth process detail per GIA and current trade buying guides (Ritani, Rare Carat).
Can Jewellers Tell If a Diamond Is Lab-Grown?
Not by eye, and not with a loupe — lab-grown and natural diamonds are optically identical. What actually detects the difference, and why a report beats an opinion.
Do Lab-Grown Diamonds Hold Their Value?
No — and it's structural, not incidental. Why lab-grown diamond prices have kept falling since large-scale production began, and what that means for resale.
Lab-Grown Diamond Certification: What to Check on the Report
GIA stopped full 4Cs grading on lab-grown diamonds in October 2025; IGI still does. What that split means, and exactly what to check before you buy.
Compare real stones before you commit
Use Chaos to understand certificates, pricing, availability and dealer supply before asking for a specific stone.