How Are Lab-Grown Diamonds Made?

Expert Insight from MDT DESIGN Jewellers

At MDT DESIGN, our diamond graders and jewellers are often asked about the difference between natural and lab-grown diamonds. Both share the same chemical composition – pure carbon – and can look identical to the naked eye. The main difference is how they are formed.

Natural diamonds are created deep within the earth over billions of years. Lab-grown diamonds, by contrast, are manufactured in a matter of months using advanced technology designed to replicate those natural conditions.

Here, our experts explain exactly how lab-grown diamonds are made, and what this means for you when choosing your diamond.

Master jeweller inspecting a diamond with a jeweller’s loupe during diamond grading and quality assessment in Melbourne.

Two Main Methods of Creation

1. High Pressure High Temperature (HPHT)

The HPHT method mimics the natural environment in which diamonds form underground.

  • A small diamond “seed” is placed into carbon.
  • The seed is exposed to extreme heat (above 1,500°C) and intense pressure (over 1.5 million PSI).
  • The carbon melts and forms around the seed, crystallising into a larger diamond over several weeks.

2. Chemical Vapour Deposition (CVD)

CVD is a more modern technique, and one of the most common methods used today.

  • A thin slice of diamond seed is placed in a vacuum chamber.
  • Carbon-rich gases (such as methane) are introduced and heated using microwaves.
  • The gases break down, and carbon atoms layer onto the seed crystal.
  • Over time, this builds a diamond crystal atom by atom.

The 4Cs and Lab-Grown Diamonds

Lab-grown diamonds, just like natural diamonds, are graded using the 4Cs: Cut, Colour, Clarity, and Carat. They can be certified and sold with similar grading structures to natural stones.

However, this raises an important question: if diamonds can be created in a laboratory under controlled conditions, why aren’t they consistently producing flawless, top-grade stones?

The reality is that lab-grown diamonds still develop inclusions, colour tints, and irregularities during the manufacturing process. In other words, while science can replicate nature’s environment, it cannot perfect it – which is why truly flawless, colourless lab-grown diamonds remain rare, despite being man-made.

This is one of the key differences between natural rarity and manufactured supply, and why MDT DESIGN believes it’s important to educate our clients on the facts before they invest.

round brilliant cut white Diamond being held in tweezers to be inspected

Do Lab-Grown Diamonds Look the Same as Natural?

To the eye, yes – a lab-grown diamond can sparkle like a natural diamond. Both can be cut, polished, and set in jewellery. However:

  • Trained graders can identify subtle differences in growth structure.
  • Lab-grown diamonds lack the billions of years of natural formation, which is why they don’t carry the same rarity or long-term value.
  • As of 2024, the GIA has announced they will no longer certify lab-grown diamonds, which is important to note when considering documentation and future resale value.
a loose round brilliant cut diamond and a princess cut diamond

MDT DESIGN Expert Perspective

As jewellers and graders, we believe it’s vital to educate our clients so they can make an informed decision.

  • Lab-grown diamonds may be a more affordable option, with visual beauty similar to natural stones.
  • Natural diamonds, however, remain unmatched in terms of rarity, history, and their ability to retain long-term value.

Whichever path you choose, we ensure complete transparency. Every diamond offered by MDT DESIGN – natural or lab-grown – has been individually inspected by our experts to ensure maximum brilliance and quality.

Choosing with Confidence

An engagement ring or fine jewellery piece is a decision that stays with you for life. That’s why we take the time necessary to explain the difference between natural and lab-grown diamonds, show you examples side by side, and guide you to the choice that aligns with your values, style, and budget.

And with our Love at First Sight Guarantee, if you propose with a diamond and your partner prefers a different shape, size, or type, we can remake the design or offer a full credit – ensuring the final piece is always perfect.

boutique

Visit MDT DESIGN in Melbourne

Our award-winning jewellers invite you to visit our Collins Street boutiqueto view both natural and lab-grown diamonds in person. Contact us to speak with one of our diamond experts, learn how each stone is formed, and feel confident in the choice you make.