CVD vs HPHT_ Difference Between the Two Diamond Growth Methods

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CVD vs HPHT: Difference Between the Two Diamond Growth Methods
I still remember the first time a customer asked me, quite earnestly, “Are these CVD or HPHT?”
It caught me off guard. A few years ago, almost no one outside the diamond industry would’ve known what those letters meant. Now, it’s one of the most common questions I get across the counter at our Sydney studio.
And honestly, it’s a good question. With the rise of lab diamonds, people are getting smarter — and more curious — about how their stones are made. These are not the cheap, glassy imitations people used to associate with “fake diamonds.” These are real diamonds, with the same chemical and optical structure as those pulled from the ground.
But when it comes to CVD vs HPHT, there’s still a lot of confusion.
So let’s pull back the curtain a little. I’ll explain what these terms actually mean, how they differ, and — maybe most importantly — whether it even matters which one you choose.
First things first: what are lab-grown diamonds, really?
If you’re new to the world of lab diamonds, it’s worth clarifying something right from the start — they’re not “synthetic” in the way you might think. A lab diamond isn’t an imitation like cubic zirconia or moissanite. It’s a diamond in every scientific sense.
The only difference is where it’s made. Natural diamonds form deep beneath the earth’s surface over billions of years. Lab diamonds, on the other hand, are grown in controlled environments using advanced technology that replicates those same natural conditions — extreme heat and pressure or a carbon-rich plasma environment.
The result? A diamond that’s physically, chemically, and optically identical to one mined from the earth. Even professional gemologists often need advanced instruments to tell the difference.
I always say to clients: it’s a bit like comparing rainwater caught in a tank to water from a natural spring. Both are H₂O — one just took a different path to get there.
The two main methods: HPHT and CVD
Now, here’s where things get interesting. There are two main ways to grow a lab diamond: HPHT (High Pressure High Temperature) and CVD (Chemical Vapour Deposition). Both produce real diamonds, but they use very different processes.
HPHT: the old-school powerhouse
The HPHT method was the first to be developed — dating back to the 1950s, actually. In the beginning, it was mainly used for industrial purposes, like making diamond-tipped drill bits. But as technology advanced, it became capable of producing gem-quality stones.
In simple terms, HPHT mimics the natural way diamonds form underground. Carbon is placed in a small chamber and subjected to extreme heat (about 1,500°C) and massive pressure — imagine over a million pounds per square inch. Under those conditions, carbon atoms bond together into a crystalline structure, and voilà — a diamond begins to form around a small seed crystal.
HPHT diamonds often grow in a cuboctahedral shape, meaning they can have slightly different growth patterns and colour zoning compared to natural stones.
They tend to start with a slight yellowish tint because the process can introduce traces of nitrogen. That’s why many HPHT diamonds are treated afterward to achieve a whiter, more colourless appearance.
CVD: the new-age approach
CVD, or Chemical Vapour Deposition, is the newer method — and it’s gained a lot of traction in the last decade. The process sounds like something straight out of a sci-fi film. A thin diamond “seed” is placed inside a sealed chamber filled with carbon-rich gases, like methane.
The chamber is heated to around 800°C, and the gases break down, allowing carbon atoms to slowly settle and crystallise on the seed layer by layer. Over a few weeks, those layers build up into a complete diamond.
What’s fascinating about CVD is the precision. The environment can be tightly controlled, which often results in very high clarity and minimal inclusions. The diamonds also tend to have less metallic content compared to HPHT stones, which can be a plus for certain technical or optical uses.
Many of the top jewellery houses now use CVD-grown diamonds because the process is efficient, consistent, and produces beautifully clean stones.
So, CVD vs HPHT — which is better?
Ah, the million-dollar question.
If you’ve spent any time researching online, you’ve probably come across heated debates about this — and, frankly, a lot of misinformation.
The truth? Both methods can produce stunning, top-quality diamonds.
But they each come with their own quirks.
HPHT diamonds often have exceptional colour saturation and can look very similar to high-grade natural stones. They’re also more thermally stable, which makes them suitable for industrial and scientific applications.
CVD diamonds, on the other hand, typically offer higher purity and fewer inclusions. Because the process is more controlled, CVD stones often start with a brownish hue that can be treated to achieve a perfectly colourless finish.
The main thing to remember is that the quality of a lab diamond depends more on the manufacturer than on the method. Just as not all mined diamonds are equal, not all lab-grown ones are either.
If you’re interested in diving deeper into the science and the subtle differences, there’s a really thorough breakdown here: cvd vs hpht. It’s one of the clearest explanations I’ve seen written for a general audience.
How can you tell the difference?
In short: you probably can’t — not with the naked eye.
Even as a jeweller, I rely on advanced tools to tell them apart. A gemological lab can use spectroscopy or fluorescence analysis to identify growth patterns unique to each method. HPHT diamonds, for instance, might show a distinct cross-shaped pattern under polarised light, while CVD stones can display parallel striations.
But from a practical standpoint?
When you’re admiring a finished diamond set into a ring, pendant, or pair of earrings, the difference is virtually impossible to see.
And, honestly, most clients care more about the cut, clarity, and sparkle than the technical details of how it was grown.
Why people are choosing lab diamonds now
This is the part that really excites me. Over the last few years, I’ve noticed a quiet revolution in how Australians are thinking about luxury. There’s this growing awareness — not just about sustainability, but about value, ethics, and transparency.
Lab-grown diamonds fit beautifully into that shift. They’re conflict-free, traceable, and often more affordable than mined diamonds of comparable size and quality.
Couples planning weddings, in particular, love the idea that they can choose a diamond that’s both ethical and exquisite. If you want to see a real-world example of how stunning they can look, check out this gorgeous feature on lab diamonds — it perfectly captures how modern, elegant, and authentic these stones can be in fine jewellery.
And honestly? It’s refreshing to see people make choices based on personal meaning rather than tradition or marketing.
A few myths worth clearing up
Let’s address a couple of misconceptions I still hear floating around:
“Lab diamonds aren’t real diamonds.”
They absolutely are. If you put a CVD or HPHT diamond next to a mined one, they’ll be identical in hardness, brilliance, and structure. The only way to tell the difference is through specialised testing.
“They’re not as valuable.”
Well, that depends on how you define “value.” In pure monetary terms, yes — lab-grown diamonds are generally more affordable and don’t appreciate the same way as rare mined stones. But in emotional or ethical terms, they carry a value of their own. Many clients feel better knowing their stone didn’t come from destructive mining practices.
“They don’t sparkle the same.”
That’s just not true. A diamond’s sparkle (or “fire”) comes from its cut, not its origin. A well-cut CVD or HPHT diamond can have just as much — if not more — brilliance as a natural one.
The future of diamonds: a blend of science and sentiment
It’s funny — I used to think lab-grown diamondsmight be a passing trend, something that appealed to a niche crowd of eco-conscious buyers. But now, I think they’re here to stay.
Younger generations, especially in Australia, are incredibly savvy about where their money goes. They want beauty, yes, but also honesty and sustainability.
As someone who’s been in the trade for over a decade, I find that heartening. We’re seeing technology and tradition blend in the most unexpected, beautiful way. The craftsmanship of fine jewellery remains — but the materials, and the mindset, are evolving.
And that’s a good thing.
So, which should you choose?
If you’re shopping for a diamond, my advice is simple: don’t get too hung up on the method. Whether it’s CVD or HPHT, focus on what really matters — how the diamond looks, how it’s cut, and how it makes you feel when you see it.
Ask your jeweller for transparency, yes, but also trust your own eye. A diamond is meant to be loved, not over-analysed.
Personally, I’ve set both types into engagement rings, earrings, even heirloom-style necklaces, and every single one of them has shone just as brilliantly as any mined stone.
At the end of the day, the beauty of a diamond — whether it was born deep underground or inside a laboratory — comes down to the light it reflects and the story it tells.
And, well, that’s something no machine can replicate.