What Exactly Is a Lab Grown Diamond?
A lab grown diamond is a real diamond. It’s made of pure carbon, with atoms arranged in the same isometric cubic system as a natural diamond. That structure is what gives it its brilliance, fire, and a perfect 10 on the Mohs hardness scale. Put it under a diamond tester, and it passes. No difference.
The Federal Trade Commission defines a diamond by its composition and crystal structure, not where it forms. So whether it’s a mined diamond or a lab created diamond, if it’s carbon crystallized this way, it’s a diamond. Chemically identical. Physically identical. Optically identical.
Most lab diamonds fall into Type IIa. That’s the purest category of diamond, with little to no nitrogen. In simple terms, you get exceptional clarity and color without the common impurities found in many earth-grown stones. Only about 2% of mined diamonds qualify as Type IIa, which makes this a quiet advantage most buyers miss.
Also worth clearing up: this is not cubic zirconia or moissanite. Those are diamond simulants, different materials with different properties.
High Pressure High Temperature Method (HPHT)
The HPHT method recreates how a natural diamond forms deep inside the earth, just inside a controlled laboratory environment. It starts with a tiny diamond seed, placed into a carbon source, usually pure graphite. Think of it as planting a crystal that will grow under the right conditions.
That environment is intense. Temperatures hit 1,300 to 1,600°C, with pressure around 5–6 GPa. That’s roughly 1.5 million PSI, comparable to balancing a commercial airplane on your fingertip. Under this extreme pressure and heat, carbon atoms melt and begin to crystallize around the seed, forming a rough diamond.
This process uses specialized machines such as a cubic press, belt press, or split-sphere (BARS) press. Originally developed in the 1950s for industrial diamonds, it now produces gem-quality stones in about 2 to 4 weeks, not billions of years.
HPHT diamonds are real diamonds, but they can carry subtle signatures. Some show a slight yellow tint from nitrogen, while others may have a faint blue nuance due to boron. You might also find metallic inclusions, a byproduct of the growth environment, which gem labs like GIA or IGI use during certification.
Once formed, the diamond crystal goes through cutting and polishing, just like any mined diamond used in fine jewelry.
Chemical Vapor Deposition (CVD)
The CVD method feels closer to precision engineering than geology. It starts with a thin diamond seed placed inside a sealed vacuum chamber, creating a tightly controlled laboratory environment for diamond growth.
That chamber is filled with carbon-rich gas, usually methane mixed with hydrogen. Heat it to around 700 to 1,200°C, then introduce microwaves or lasers. This turns the gas into plasma, an energized, ionized state where carbon atoms break free.
Those carbon atoms don’t float around randomly. They attach to the seed and begin to crystallize layer by layer, building a diamond crystal one atomic sheet at a time. Think of it like 3D printing, but with pure carbon forming a real diamond.
Growth takes about 2 to 6 weeks, depending on the size you’re aiming for. The big advantage is control. You can fine-tune conditions to reduce nitrogen, limit metallic inclusions, and produce diamonds with better color and clarity, often in the Type IIa range.
Once the rough diamond is formed, it goes through cutting and polishing, then grading and certification by labs like IGI or GIA.
Every EthicStone diamond is lab grown using HPHT or CVD technology, IGI certified for cut, color, clarity, and carat, and priced without inflated middleman markups.
CVD vs HPHT: Which Method Is Better?
Neither. That's the honest answer.
Both chemical vapor deposition and high pressure high temperature produce real diamonds which is chemically identical, physically identical, and optically identical to mined diamonds. Both pass a diamond tester every single time. If you've seen claims online that HPHT stones somehow fail testers, that's a myth. A diamond is a diamond, regardless of which lab method created it.
The difference is in what each method does best. HPHT excels at producing smaller, high-quality stones with excellent color. The trade-off? Metallic inclusions from the catalyst metals used during growth, and occasionally a faint blue nuance from trace boron. CVD diamonds tend to grow larger with fewer inclusions, but some come out with a slight brown tint. That's why many CVD stones undergo post-growth HPHT treatment to improve their color before cutting and polishing.
Here's how the two methods stack up side by side:
| Property | HPHT | CVD |
|---|---|---|
| Temperature | 1,300 – 1,600 °CMimics Earth's mantle conditions | 700 – 1,200 °CLower temp, plasma-driven |
| Pressure | ~5–6 GPa (extreme)Intense | Low pressureVacuum chamber environment |
| Growth Time | Days to weeksFaster for smaller stones | 2 – 4 weeksLarger stones take longer |
| Common Inclusions | Metallic inclusionsFrom catalyst metals (iron, nickel) | Minimal inclusionsCleaner |
| Color Tendencies | Strong whitesPossible blue nuance from boron | Can skew brownishTreatable with post-growth HPHT |
| Best For | Smaller stones (<2 ct)Quality | Larger stones (2 ct+)Size |
| Post-Growth Treatment | Rarely needed | Often HPHT-treatedTo improve color grades |
| Diamond Tester | Passes — real diamond | Passes — real diamond |
Temperature
HPHT1,300 – 1,600 °C
CVD700 – 1,200 °C
Pressure
HPHT~5–6 GPa (extreme)
CVDLow (vacuum chamber)
Growth Time
HPHTDays to weeks
CVD2 – 4 weeks
Common Inclusions
HPHTMetallic (catalyst metals)
CVDMinimal
Color Tendencies
HPHTStrong whites; possible blue nuance
CVDCan skew brownish; treatable
Best For
HPHTSmaller stones (<2 ct)
CVDLarger stones (2 ct+)
Post-Growth Treatment
HPHTRarely needed
CVDOften HPHT-treated
Diamond Tester
HPHT✅ Passes
CVD✅ Passes
EthicStone sources from both methods — we pick whichever produces the best stone.
Every diamond is IGI-certified and graded across all 4Cs.
Every diamond is IGI-certified and graded across all 4Cs.