The Complete Guide to the Diamond-Growing Process

How Are Lab-Grown Diamonds Made?

From a single diamond seed to a certified, finished stone — the science, the timeline, and everything you need to know before you buy.

Quick Answer

Lab-grown diamonds are created in a laboratory using one of two advanced processes: High Pressure High Temperature (HPHT) or Chemical Vapour Deposition (CVD). Both methods replicate the natural conditions deep within the Earth, producing diamonds that are chemically, physically, and visually identical to mined diamonds. The process typically takes several weeks from start to finish.

📋 Key Takeaways

Lab-grown diamonds are real diamonds — not imitations or simulants
They are created using two methods: HPHT and CVD
Both processes begin with a tiny diamond seed and add carbon atom by atom
Most quality lab-grown diamonds take several weeks to grow
After growth, they are cut, polished, and graded exactly like mined diamonds
They are chemically and physically identical to diamonds formed in the Earth
Lab-grown diamonds typically cost 50–80% less than mined diamonds of the same quality

📖 In This Guide

What Is a Lab-Grown Diamond?
Are Lab-Grown Diamonds Real Diamonds?
How Are Lab-Grown Diamonds Made?
HPHT vs CVD: Side-by-Side Comparison
From Diamond Seed to Finished Diamond: The Full Journey
How Long Does It Take to Make a Lab-Grown Diamond?
Are Lab-Grown Diamonds Treated After Growth?
Why Are Lab-Grown Diamonds Cheaper?
Can You Tell the Difference?
Are Lab-Grown Diamonds Sustainable?
How the Technology Is Evolving
Common Myths About Lab-Grown Diamonds
Who Should Choose a Lab-Grown Diamond?
Step-by-Step: The Process at a Glance
Frequently Asked Questions

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What Is a Lab-Grown Diamond?

A lab-grown diamond is exactly what it sounds like: a genuine diamond that has been grown in a laboratory rather than extracted from the ground. It is not a diamond simulant like cubic zirconia or moissanite. It is not glass. It is a real diamond.

The only difference between a lab-grown diamond and a mined diamond is where it was created. One grew under the Earth over billions of years. The other was grown in a controlled environment over several weeks. But when it comes to the science — the chemistry, the crystal structure, the hardness, the brilliance — they are absolutely identical.

Here is where things get interesting. Even expert gemmologists cannot tell the difference between a lab-grown diamond and a mined diamond using the naked eye alone. Standard jeweller's tools do not reveal the difference either. Only highly specialised laboratory equipment, designed specifically for this purpose, can identify which is which.

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Are Lab-Grown Diamonds Real Diamonds?

Direct Answer

Yes. Lab-grown diamonds are real diamonds. They have the same chemical composition (pure carbon), the same crystal structure (cubic), the same hardness (10 on the Mohs scale), and the same optical properties as mined diamonds. The Gemological Institute of America (GIA) and the International Gemological Institute (IGI) both recognise and certify lab-grown diamonds as genuine diamonds.

This question comes up time and again, and it is completely understandable. When something is made in a laboratory, it is natural to wonder whether it is somehow lesser or artificial. But the answer is clear: lab-grown diamonds are real diamonds in every scientific sense of the word.

Carbon atoms bonded together in a specific crystal structure are what make a diamond a diamond. Whether those atoms bonded deep underground or inside a growth chamber makes no difference to the resulting material. The diamond is the diamond.

What Lab-Grown Diamonds Are NOT

Cubic zirconia (which is zirconium dioxide, not carbon)
Moissanite (which is silicon carbide, not carbon)
Glass or any other simulant
Coatings or thin films applied to another material

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How Are Lab-Grown Diamonds Made?

To understand how lab-grown diamonds are made, it helps to understand how natural diamonds form. Deep in the Earth — roughly 100 miles below the surface — extreme heat (over 1,000°C) and immense pressure cause carbon atoms to bond together in a unique crystal structure. This process takes billions of years. Volcanic activity then pushes these diamonds closer to the surface, where they are eventually mined.

Lab-grown diamonds replicate those same extreme conditions — just in a controlled environment, and in weeks rather than billions of years. There are two main methods: High Pressure High Temperature (HPHT) and Chemical Vapour Deposition (CVD). Both begin with a tiny diamond seed. Both end with a rough diamond crystal that is then cut and polished into the stone you see in a ring or necklace.

Infographic showing how lab-grown diamonds are made, from diamond seed through HPHT and CVD growth to cutting, polishing and certification — How lab-grown diamonds are made: from seed to certified stone

Method 1

High Pressure High Temperature (HPHT)

Developed in the 1950s by General Electric, HPHT recreates the enormous heat and pressure found deep inside the Earth.

A diamond seed sits inside a growth cell with a carbon source and a metal catalyst (iron, cobalt, nickel)
A mechanical press generates 1.5–2 million PSI (roughly 5–6 GPa)
The chamber heats to 1,300–1,600°C
The molten catalyst dissolves carbon and transports it to the seed
Carbon bonds to the seed layer by layer over several weeks

Method 2

Chemical Vapour Deposition (CVD)

The newer method. Instead of extreme pressure, CVD grows diamonds from a carbon-rich gas inside a vacuum chamber.

A thin diamond seed sits inside a sealed vacuum chamber
The chamber fills with methane and hydrogen gas
Heated to 700–1,200°C — far lower than HPHT
Microwave energy or a plasma torch ionises the gas into plasma
Carbon atoms rain onto the seed, building the crystal one atom at a time

💡 Think of It This Way

Growing a lab diamond is like growing a crystal in nature, only accelerated in a controlled environment. The atoms do not know whether they are deep underground or inside a laboratory press — they simply follow the same physical laws either way.

Advantages & Challenges at a Glance

Method	Advantages	Challenges
HPHT	Well-established, decades-long track record. Lower production cost for smaller stones. Effective for treating existing diamonds to improve colour.	Enormous, expensive presses. Harder to achieve large colourless stones. Metal catalysts can leave trace inclusions.
CVD	Produces large, colourless diamonds more consistently. Less extreme equipment. Fewer inclusions. Increasingly powered by renewable energy.	High initial equipment costs. Can produce brown tints needing HPHT treatment. Sometimes slower than optimised HPHT setups.

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HPHT vs CVD: Side-by-Side Comparison

Surprisingly, neither method is universally better. Both produce genuine, high-quality lab-grown diamonds. The choice often depends on the size and colour grade you're looking for, with CVD increasingly preferred for larger, colourless gem-quality stones.

Feature	HPHT	CVD
Process	Extreme heat and pressure mimicking deep-Earth conditions	Grows diamond from carbon-rich gas in a vacuum chamber
Growth Speed	Often 2–4 weeks	2–4 weeks, but more controllable
Typical Size	Often used for stones under 1 carat	Better suited for 1 carat and above
Colour Consistency	Can produce yellow/brown tones, often needs treatment	Generally higher-quality colourless output
Cost	Slightly lower production cost	Higher equipment cost but scalable
Most Common Use	Industrial applications, some gem-quality stones	Gem-quality diamonds for jewellery
Post-Growth Treatment	Less common	HPHT treatment sometimes used to improve colour

If you'd like to see how lab-grown stones stack up against mined diamonds more broadly, our lab vs natural diamonds comparison guide covers price, sparkle, and resale value in detail.

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From Diamond Seed to Finished Diamond: The Full Journey

Most discussions of lab-grown diamonds focus on the growth chamber — but that is only part of the story. Here is the complete journey, from the very first step to the moment a diamond is set into a piece of jewellery.

Diamond Seed Creation

Every lab-grown diamond begins with a tiny sliver of an existing diamond, typically less than a millimetre thick. Seeds are usually grown from earlier lab-grown diamonds, creating a chain of diamond growth. Any impurities at this stage can affect the quality of the final stone.

Growth Chamber

The seed is placed inside a chamber calibrated to the chosen method — a high-pressure press for HPHT, or a vacuum reactor for CVD. Engineers monitor temperature, pressure, and gas composition continuously.

Crystal Growth

The longest stage. Over several weeks, carbon atoms bond to the seed, layer by layer, following the same crystal lattice as a natural diamond. Growth must be slow and controlled — rushing it produces lower-quality stones.

Rough Diamond Extraction

Once growth is complete, the rough diamond is carefully removed. It looks nothing like the gem you'd see in a shop — an irregular, cloudy crystal with remarkable quality waiting to be revealed.

Cutting and Planning

Expert diamond cutters study the rough stone using computer-aided design software, planning the optimal cut to maximise brilliance, minimise waste, and retain carat weight.

Polishing

The diamond is cut and polished with diamond-tipped tools — nothing else is hard enough. A round brilliant requires 57 or 58 individual facets, each polished to precise angles.

Grading and Certification

The polished diamond is sent to an independent laboratory — most commonly IGI or GIA. Gemmologists assess the four Cs: cut, colour, clarity, and carat weight.

Jewellery Setting

Finally, the certified diamond is set into a piece of jewellery by a skilled craftsperson — an engagement ring, pendant, or pair of earrings.

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How Long Does It Take to Make a Lab-Grown Diamond?

Direct Answer

From seed to certified diamond, most quality lab-grown diamonds take between 8 and 16 weeks in total. The growth phase alone typically takes 2 to 6 weeks, depending on the method and the desired carat size. Larger diamonds take longer to grow than smaller ones.

Surprisingly, a lab-grown diamond does not appear overnight. While the technology is advanced, growing a genuine diamond — even in a laboratory — requires patience. Here is a typical timeline:

Stage	Duration	What Happens
1. Seed Preparation	1–3 days	A tiny diamond seed is cleaned, polished, and prepared for placement in the growth chamber.
2. Chamber Setup	1–2 days	For HPHT, the seed is loaded into a press. For CVD, it's placed in a vacuum reactor and calibrated.
3. Crystal Growth	2–6 weeks	Carbon atoms slowly bond to the seed, layer by layer. The longest stage — most quality diamonds take 3–4 weeks.
4. Rough Extraction	1–2 days	The rough diamond is removed from the chamber and inspected for quality, colour, and clarity.
5. Cutting & Planning	1–2 weeks	Expert cutters analyse the rough stone and plan the best cut for brilliance and weight retention.
6. Polishing	3–7 days	The diamond is cut and polished to its final shape using specialist equipment.
7. Grading & Certification	2–4 weeks	The finished diamond is sent to IGI or GIA for assessment against the 4 Cs.
8. Jewellery Setting	1–3 weeks	Once certified, the diamond is set into your chosen piece by a skilled craftsperson.

Larger diamonds take proportionally longer. A 3-carat lab-grown diamond might take twice as long to grow as a 1-carat stone. The certification process at laboratories like IGI can also take several weeks, particularly during busy periods.

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Are Lab-Grown Diamonds Treated After Growth?

Direct Answer

Yes, some lab-grown diamonds — particularly those grown via CVD — undergo post-growth HPHT treatment to improve their colour. This is a standard industry practice, and treated diamonds remain genuine diamonds. Reputable retailers and grading certificates will disclose this.

Colour Enhancement

CVD-grown diamonds sometimes develop a brown or greyish tint during growth, caused by structural distortions in the crystal lattice. To correct this, the rough diamond undergoes HPHT treatment — high heat and pressure that rearranges the crystal structure and eliminates the colour defects. The result is a colourless or near-colourless diamond that would otherwise have been significantly less valuable. The treatment is permanent and does not affect the long-term appearance or durability of the stone.

Clarity Improvement

In some cases, treatments may also be used to improve clarity by reducing the visibility of inclusions — though this is less common than colour treatment.

What This Means for Buyers

Always buy from a retailer who provides a full grading certificate from IGI or GIA
The grading certificate will state whether the diamond has been treated
Post-growth treatment does not make a diamond less genuine — it is a processing step, not a disguise
Treated and untreated lab-grown diamonds are both real diamonds

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Why Are Lab-Grown Diamonds Cheaper?

Direct Answer

Lab-grown diamonds are typically 50–80% less expensive than mined diamonds of the same quality because they require no mining infrastructure, have a shorter and simpler supply chain, and can be produced in greater quantities as demand grows.

This is one of the most common questions buyers have — and it is a fair one. If lab-grown diamonds are real diamonds, why do they cost so much less?

No Mining Infrastructure

Mining diamonds requires enormous capital investment: excavating mines, heavy machinery, land acquisition, global logistics, and the labour of thousands of workers. None of this applies to lab-grown diamonds. The "mining" happens inside a growth chamber the size of a large kitchen appliance.

Shorter Supply Chain

Mined diamonds pass through many hands: mining companies, sorting facilities, rough diamond traders, polishing factories, wholesalers, and retailers. Each step adds cost. Lab-grown diamonds go from growth facility to polisher to retailer — a fraction of the steps.

Greater Availability

Natural diamonds are scarce, and scarcity drives price. Lab-grown diamonds can be produced in increasing quantities as facilities expand. Greater supply means lower prices, particularly as the technology matures.

Faster Production

A natural diamond takes billions of years to form. A lab-grown diamond of the same quality takes weeks. That alone fundamentally changes the economics.

💡 Finediam Tip

The lower price does not reflect lower quality. A lab-grown diamond costing 60% less than a mined diamond of the same grade is not inferior — it is the same stone, at a different price. Browse our lab-grown diamond collection to compare for yourself.

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Can You Tell the Difference Between Lab-Grown and Natural Diamonds?

Direct Answer

No. Lab-grown and mined diamonds are visually identical. Even trained gemmologists cannot tell them apart with standard tools. Only advanced laboratory equipment, specifically designed for this purpose, can identify the difference — and even then, it requires looking for very subtle internal characteristics.

At this point, you might be wondering whether anyone can actually tell the difference. The short answer is: not without highly specialised equipment.

A standard jeweller's loupe will not reveal the difference
A gemmological microscope will not reveal the difference
A refractometer, spectroscope, or thermal conductivity tester will not reveal the difference
Only instruments such as De Beers' DiamondView or similar photoluminescence spectrometers can detect subtle differences in growth patterns or trace element composition

This equipment costs tens of thousands of pounds and is only found in professional grading laboratories. Your local jeweller almost certainly does not have it — and would not need it.

The grading certificate that accompanies a lab-grown diamond will clearly state that it is laboratory-grown. This is the only reliable way to know what you have.

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Are Lab-Grown Diamonds Sustainable?

Direct Answer

Lab-grown diamonds are generally more sustainable than mined diamonds in terms of land disruption, water use, and community impact — but their environmental footprint depends significantly on the energy source used to power the growth facilities. Not all lab-grown diamonds are equally green.

Sustainability is one of the most discussed aspects of lab-grown diamonds — and one of the most nuanced. Here is an honest assessment.

✅ Where Lab-Grown Diamonds Win

No open-cast mines, reducing land disruption and habitat destruction
No processing of enormous quantities of rock to find tiny gemstones
Significantly lower water use compared to mining operations
No risk of community displacement or conflict sometimes associated with mined diamonds
No carbon emissions from mining vehicles, transport, and global logistics

⚠️ The Honest Caveats

Growing diamonds requires significant energy — presses and reactors run continuously for weeks
If that energy comes from fossil fuels, the carbon footprint can be substantial
Not all facilities use renewable energy — sustainability depends on where and how a stone was grown
The industry as a whole continues to work towards greater transparency on this

The most environmentally responsible lab-grown diamonds are those produced in facilities powered by renewable energy, such as solar or wind. Some producers now highlight this on their websites and certificates — it is worth asking your retailer if this matters to you.

The Bottom Line

Lab-grown diamonds are generally a more sustainable choice than mined diamonds — but they are not carbon-neutral by default. The specifics matter.

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How Lab-Grown Diamond Technology Is Evolving

The lab-grown diamond industry has advanced rapidly since the first gem-quality stones were produced commercially in the 1990s. And the pace of change is accelerating.

Larger Diamonds

Early CVD and HPHT facilities struggled to produce diamonds above 1 carat economically. Today, 3, 4, and even 5-carat lab-grown diamonds of exceptional quality are routinely available. As growth processes are refined, even larger stones will become accessible.

Better Colour Consistency

Producing consistently colourless diamonds — graded D, E, or F on the GIA colour scale — has historically been a challenge. Advances in plasma control and growth environment management are making this more achievable and more affordable.

Lower Production Costs

As with most technologies, costs fall as understanding deepens and processes are streamlined. Lab-grown diamond prices have dropped significantly over the past decade and are likely to continue falling, making exceptional diamonds accessible to an even broader range of buyers.

Renewable-Energy Powered Facilities

A growing number of producers are transitioning to 100% renewable energy sources, dramatically reducing the carbon footprint of each diamond. This makes the sustainability case for lab-grown diamonds even stronger.

Industrial Applications

Beyond jewellery, lab-grown diamonds are increasingly important in technology — as semiconductors, in medical equipment, in quantum computing research, and in cutting tools. This broader demand is driving further investment in manufacturing capability.

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Common Myths About Lab-Grown Diamonds

There are a surprising number of misconceptions about lab-grown diamonds circulating online and in jewellery shops. Here is the truth.

MYTH: Lab-grown diamonds are fake. REALITY: They are real diamonds. Lab-grown diamonds have the same chemical composition, crystal structure, physical properties, and optical characteristics as mined diamonds. The only difference is origin.

MYTH: They will not last as long as real diamonds. REALITY: Diamonds — mined or lab-grown — score 10 on the Mohs hardness scale, the maximum. A lab-grown diamond is just as hard, just as durable, and just as scratch-resistant as any mined diamond. It will last a lifetime.

MYTH: You can easily spot a lab-grown diamond. REALITY: You cannot — not without highly specialised laboratory equipment costing tens of thousands of pounds. Even professional gemmologists cannot tell the difference with standard tools.

MYTH: Lab-grown diamonds have no resale value. REALITY: Like all diamonds, lab-grown stones do not typically appreciate in value, but they do have resale value proportionate to current market price. This is also true of mined diamonds, whose resale value has declined significantly in recent decades.

MYTH: Lab-grown diamonds are not certified. REALITY: Reputable lab-grown diamonds are fully certified by internationally recognised grading laboratories, including IGI and GIA. These certificates assess cut, colour, clarity, and carat weight — exactly the same criteria applied to mined diamonds.

MYTH: All lab-grown diamonds are perfect. REALITY: This is not true. Like mined diamonds, lab-grown diamonds come in a range of qualities. Some have inclusions, some have colour tints, and some are cut better than others. The grading certificate tells you exactly what you are getting.

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Who Should Choose a Lab-Grown Diamond?

Lab-grown diamonds are not the right choice for everyone — but they are the ideal choice for a significant and growing number of buyers. Here is an honest guide to who benefits most.

Engagement Ring Buyers

Same visual impact and emotional significance as mined diamonds — often for 50–80% less. Your budget goes much further on carat size and quality.

Budget-Conscious Shoppers

Want a beautiful, certified diamond without stretching your finances? Lab-grown is the smart choice — real diamond quality at a fraction of the price.

Sustainability-Focused Buyers

Avoids the land disruption and community impact associated with mining. Just ensure your chosen stone comes from a facility using renewable energy.

Lovers of Larger Stones

Because lab-grown diamonds cost significantly less per carat, you can choose a noticeably larger stone for the same budget.

Modern, Forward-Thinking Shoppers

Lab-grown diamonds represent the future of fine jewellery — a purchase that reflects cutting-edge science and innovation.

Gift Buyers

For birthdays, anniversaries, or milestone occasions, lab-grown diamonds offer exceptional value without overspending.

On the other hand, if provenance and tradition matter greatly to you — if owning a stone formed by natural geological processes over billions of years is part of what makes it meaningful — then a mined diamond may be the right choice. Both are genuine diamonds. The decision is a personal one. Our lab-grown vs natural diamonds guide can help you weigh up the two.

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Step-by-Step: How a Lab-Grown Diamond Is Created

The 8-Step Process at a Glance

Select a diamond seed — a tiny sliver of existing diamond
Place the seed inside a growth chamber (HPHT press or CVD reactor)
Add the carbon source (graphite for HPHT; methane gas for CVD)
Apply extreme heat and pressure (HPHT) or plasma energy (CVD)
Allow the diamond crystal to grow over 2–6 weeks
Remove the rough diamond and plan the optimal cut
Cut and polish the diamond using diamond-tipped tools
Send to IGI or GIA for grading and certification

Ready to Explore Lab-Grown Diamonds?

Every lab-grown diamond at Finediam is independently certified by IGI or GIA and hand-set by our craftspeople in Hatton Garden, London.

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