Lab Grown Diamonds

How are lab grown diamonds made?

Discover the two processes that'll help you answer the questions "how are lab grown diamonds made?", CVD and HPHT. Learn how scientists have created a way to mimic the natural growth of a diamond within a laboratory, and how these processes produce authentic lab diamonds, identical to those found in nature.

How are diamonds made in a lab?

Laboratory made diamonds are created in an artificial setting that mimics how diamonds are made naturally below the Earth’s mantle. There are two methods used to create lab diamonds: CVD (chemical vapour deposition) and HPHT (high pressure high temperature). Both methods are effective in creating high-quality, authentic diamonds, identical to those found in nature.

During CVD diamond creation, a minuscule slice of diamond is placed into a chamber where it is exposed to carbon-rich gas and amped up to extremely high temperatures. Over a matter of just weeks, the carbon gas ionises and the particles stick to the original diamond slice, before eventually crystallising into a fully formed diamond.

CVD diamond (left), HPHT diamond (centre), natural diamond (right)

During HPHT, pure carbon is pressed within a metal cube and exposed to immense heat and pressure through electric pulses. Eventually, the carbon breaks down and crystallises into a diamond. Any metal traces within a HPHT diamond will be minuscule and usually not visible to the naked eye.

Most experts agree that HPHT diamonds are better quality than CVD diamonds. CVD diamonds are fast growing, which can cause spotty internal marks and graining. CVD diamonds are also known to have brown-ish undertones when produced, meaning they must undergo post-growth treatment to enhance their beauty. HPHT diamonds are typically produced at a higher standard, without the requirement for post-growth treatment.

In the same way as natural diamonds, lab diamonds go through strict grading assessment during certification, by grading laboratories like GIA and IGI. This means you can filter your diamond search by the usual cut, colour and clarity standards - so you can find a lab diamond equally beautiful as a top quality natural diamond. Top tip - look a lab diamonds with the grades Excellent cut, D to F colour and VS2 to SI1 clarity for a beautiful stone at the best price.

Where are lab diamonds made?

As you might expect, lab diamonds, or synthetic diamonds, are made within laboratories. These laboratories are highly specialised, operated by incredibly skilled scientists and engineers, using cutting-edge technology. These are located around the globe in countries like the USA, China, India and Israel. Queensmith sources lab diamonds from a number of reputable producers across the globe, some of whom produce and use solar energy to power or offset the production of their diamonds.

In many ways, the production of diamonds within a lab is more sustainable than diamond mining. Man made take a great deal of energy to grow, but technologies are constantly improving to become more efficient, and lab diamond producers, like Diamond Foundry use renewable energy to power their production. Natural diamond mines require vast expanses of land to explore and excavate, and once the land is mined it could take decades to become arable or usable land once again. On the contrary, a human-made diamond lab requires a relatively small amount of land and can go on producing diamonds without the need for expansion or land development.

More about lab diamonds vs natural diamonds.

What is a lab grown diamond made of?

Carbon! Just like natural diamonds, lab diamonds are made of pure unadulterated carbon. During the creation of human-made diamonds, carbon atoms form in a structure identical to that of natural diamonds. Synthetic diamonds are sometimes referred to as carbon made diamonds - but the reality is, both natural and lab diamonds are made from carbon. With their identical internal structure and physical optics, the only way to tell a lab diamond from a natural diamond is with specialist equipment.

CVD vs HPHT diamonds

Generally speaking, HPHT diamonds are produced with more ideal aesthetics and are deemed higher quality in most instances.

For the producer, the CVD process is quicker, less costly and uses less energy, so it is often pushed as the 'better' method of diamond production. The reality is, this fast process typically produces a lower quality gem. The common traits of a CVD diamond include brown under tones, spotty inclusions and internal graining. Where such undesirable traits exist, the diamond will usually undergo a post-growth HPHT treatment. However, removing these flaws with post-growth treatment can make the diamond then appear milky and hazy.

We highly recommend looking for an HPHT lab created diamond for your engagement ring or special jewellery. That is not to say you should totally avoid CVD diamonds - a high quality CVD diamond that hasn't needed post-growth treatment will appear bright, sparkly and beautiful. Compare a CVD diamond that hasn't required post-growth treatment with an HPHT diamond of the exact same cut, colour and clarity grades, and you won't be able to tell them apart. You can see whether a diamond has undergone post-growth treatment on its IGI or GIA certificate, or get in touch to ask an expert.

Chemical Vapour Deposition (CVD) lab grown diamond process

  1. A thin slice of diamond is selected, 300 microns thick and around 10x10mm. This diamond slice is typically taken from an already lab created diamond

  2. The diamond slice is thoroughly cleaned, as any defects will grow with the diamond, forming inclusions

  3. The diamond slice is injected into a chamber

  4. The chamber is securely sealed to keep any traces of other gas out

  5. The chamber is flooded with carbon rich gas and heated to extreme temperatures

  6. At this stage, nitrogen can be added to the gas to speed up the process - but good synthetic diamond producers avoid this, as it yellows the diamond

  7. The gas reacts by breaking down, coating the diamond slice and bonding to it

  8. The chamber continues to be filled with gas over a couple of weeks, continually breaking down and coating the diamond slice, building up the carat weight

  9. A rough lab diamond is produced, which looks like a square cube

  10. The rough diamond is cut with laser precision and traditional polishing techniques into the desired shape

  11. The CVD diamond will undergo certification. Graders like GIA assess the cut, colour, clarity and carat weight, amongst other details, and certify that the diamond is lab created by CVD

High Pressure High Temperature (HPHT) lab grown diamond process

  1. Carbon (usually a small, existing diamond) is contained in a containment cube

  2. The cube is pressed to enforce the same pressure a diamond faces under the Earth’s surface

  3. The cube is intensely heated through electric pulses

  4. The heat and pressure causes the carbon to crystallise

  5. A rough lab diamond is produced in a matter of weeks, typically around one month

  6. The rough diamond is cut with laser precision and traditional polishing techniques into the desired shape

  7. The HPHT diamond will undergo certification. Graders like GIA assess the cut, colour, clarity and carat weight, amongst other details, and certify that the diamond is lab created by HPHT

From blueprint to lab-grown diamond

Video courtesy of JTV Live Now

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Related Guides

Frequently Asked Questions

About Lab Diamonds

Making Lab Diamonds

How long does it take to make a lab grown diamond?

Lab diamonds typically form between 2 and 4 weeks. The process can be quicker if other elements are introduced, like nitrogen, but this can make the diamond yellow-tinted.

Do lab diamonds test as real diamonds?

Yes, lab diamonds test as real diamonds, because they are authentic and identical to those found in nature, with the exact same chemical makeup. However, specialist laboratory equipment can tell lab diamonds from natural diamonds.

Is it possible to make a lab grown diamond at home?

No - you’d need a great deal of specialist equipment to create a lab diamond, and it could be an incredibly dangerous process in the wrong hands. It takes a wealth of knowledge for trained scientists and engineering specialists to create a lab diamond - and it’s a very exact science in which the creator must work out the precise, perfect conditions for diamond growth. The intense heat and intense pressure that takes place during lab diamond creation isn’t something you can replicate at home.

Do lab grown diamonds come in different colours?

Yes, lab diamonds can be created in a number of fancy colours, including yellow, blue, pink, orange, green, red and black. In nature, trace elements enter the otherwise pure carbon diamond to cause colouration - like boron in blue diamonds, and nitrogen in yellow diamonds. The same idea can be applied to lab diamonds, where the scientist will work out the perfect amount of trace elements to add during the diamond creation.

Buying A Lab Diamond

Where can I buy lab grown diamonds in the UK?

Queensmith is one of the first jewellers to offer lab diamond rings in the UK.

The world of lab created diamonds is still relatively untouched by the UK engagement ring market, meaning there are few retailers where you can buy lab grown diamond engagement rings and jewellery. Queensmith is at the forefront of understanding and retailing lab grown diamonds alongside our bespoke engagement ring and jewellery services.

After learning your rough budget and an idea of what you’re after, our gemmologists will work on putting together a select range of the finest lab grown diamonds for your unique budget, before meeting with you to discuss your engagement ring or jewellery design.

Book an appointment online or in-store to meet with our diamond & design experts.

What’s the sentimental value of a man made diamond?

This one is up to you. Some adore the romantic history behind naturally grown diamonds, formed over billions of years, rare, precious and perhaps nature’s most beautiful and enchanting creation. Others prioritise the ethical value of lab grown diamonds, and praise the wonder of science in creating something it took the earth billions of years to do so. It’s the power of nature versus the wonder of science - which camp are you in?

Book to discuss with an expert.

How to choose the best lab created diamond for your ring

Choosing the best lab grown diamonds for your engagement ring is no different to choosing a natural diamond. If you’ve decided a lab grown diamond engagement ring is right for you, follow these steps:

  1. define your rough budget
  2. choose the ring style you like, and minus the cost of this to see how much you can dedicate to the diamond
  3. choose the shape of lab diamond you’re after
  4. consider diamonds graded Excellent cut (for round diamonds, or Excellent polish & symmetry for other shapes), D to F colour, VS2 to SI1 clarity

You can read more about choosing the best diamond for your engagement ring here, but the characteristics to prioritise are an excellent cut, followed by a high colour grade. This will ensure that a diamond appears bright, white and extremely sparkly. When narrowing down the options for your lab grown diamond engagement ring, it’s important to seek advice from qualified gemmological experts, to help you understand the intricacies and characteristics of each diamond, point out any flaws, and help you find the best value diamonds for your unique budget. For more advice or to receive a tailored quote, get in touch with our experts.

Can I insure my lab grown diamond engagement ring?

Absolutely. Just like any high value purchase you make, it is important to insure your lab grown diamond ring. The cost of insuring your lab grown diamond is likely to be less than that of a mined diamond, and your insurer of choice will most likely need to see a copy of your order invoice to verify the value of your insurance.

Natural Vs Lab Diamonds

Are lab grown diamonds real?

Yes, lab grown diamonds are 100% authentic diamonds, they are just grown in a lab setting with conditions made to replicate what happens in nature.

Will lab created diamonds test as real diamonds?

Yes, a lab diamond will test as a real diamond - because it is chemically, physically and optically identical to a natural diamond, and is therefore a genuine diamond. Specialist equipment can be used to tell a lab diamond from a natural diamond - and the origin of a diamond is included on its certificate.

Do lab grown diamonds last as long as natural diamonds?

Yes, a lab diamond will last just as long as a natural diamond. The makeup of a lab diamond is exactly the same as a natural diamond - both measure 10 on the Mohs scale of hardness, making them the hardest natural substance on Earth. This makes them resistant to scratches, abrasion or breaking.

Why are lab grown diamonds cheaper than natural diamonds?

Lab diamonds take only a matter of weeks to form in a relatively small laboratory with a small but highly skilled workforce - whereas natural diamonds require large expanses of land, excavation, infrastructure and workforce - as well as time to find the diamonds. The reason lab diamonds are significantly cheaper than natural diamonds is that their production is far more efficient and cost-effective!

More About Lab Diamonds

Why are human-made diamonds called ‘synthetic diamonds’?

Whilst the terminology can seem a little confusing, man made, ‘synthetic diamonds’ are real diamonds - created in a lab. The term ‘synthetic diamond’ refers to the synthetic (i.e. human-made) environment in which a lab grown diamond is created.

Synthetic diamonds are not to be confused with diamond simulants. Diamond simulants are not diamonds, but are stones that are somewhat similar in appearance and are generally used for cheaper, high street jewellery, such as cubic zirconia and moissanites. Our gemmological advice is to steer clear of diamond simulants: they do not retain value, and more importantly are less striking in appearance, particularly their sparkle, lustre and crisp structure.

What else are lab grown diamonds known as?

Lab grown diamonds are referred to as synthetic diamonds, artificial diamonds, as well as man made, manufactured, lab created, engineered, cultivated and cultured diamonds. These terms all mean the same thing, but 'lab grown' is the term that is most commonly used by jewellers and jewellery buyers.

How long does it take to create a lab grown diamond?

Typically, lab grown diamonds take between one and two weeks to form. Compared to the natural process, which takes billions of years for diamonds to form and enter the Earth’s surface, it is an incredibly quick process!

CVD & HPHT Diamonds

Are CVD diamonds treated?

Most CVD diamonds are treated after creation to enhance their clarity and colour grades. In comparison, fewer lab diamonds created by HPHT need such post-growth treatment to enhance their beauty. Having said this, some CVD diamonds are perfectly gem-quality when created, meaning they don’t need to be treated. This is the same with natural diamonds. You’ll see whether a diamond has been treated on its certificate.

Are CVD diamonds real?

Yes, CVD produces authentic diamonds. A CVD diamond is not artificial - it is 100% genuine diamond, identical in every way to the diamonds found in nature. You might hear some people call CVD diamonds ‘artificial diamonds’, but this refers to the artificial environment in which they are created, rather than the diamonds themselves being fake. It is a confusing term, which is why the industry is starting to abandon the phrase.

Which is better, CVD or HPHT diamonds?

Most experts agree that HPHT diamonds are better quality than CVD diamonds. CVD diamonds are fast growing, which can cause spotty internal marks and graining. CVD diamonds are also known to have brown-ish undertones when produced, meaning they must undergo post-growth treatment to enhance their beauty. HPHT diamonds are typically produced at a higher standard, without the requirement for post-growth treatment.

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