How Are Lab Grown Diamonds Made?

Lab grown diamonds are one of the most exciting developments in modern jewellery—combining beauty, science, and sustainability. But how are they actually made?

In this guide, we’ll walk you through the two main methods of lab diamond creation—HPHT and CVD—explain the differences between them, and explore what this means for quality, value, and appearance.

Whether you're new to the concept or researching your next ring, this article will help you understand why lab grown diamonds are just as real as their mined counterparts—and often better aligned with modern values.

What Is a Lab Grown Diamond?

A lab grown diamond is a real diamond—just one created above ground in a controlled environment, rather than formed deep in the Earth’s mantle over billions of years.

It has the same atomic structure (carbon in a cubic crystal form) and identical physical, chemical, and optical properties as a mined diamond. This means:

• Same hardness (10 on the Mohs scale)

• Same brilliance and fire

• Same ability to be certified by IGI or GIA

What differs is the origin—and the remarkable science behind it.

The Two Main Growth Methods: HPHT and CVD

🔬 1. HPHT: High Pressure High Temperature

This is the original method of lab diamond production, designed to replicate the natural formation process that happens beneath the Earth’s surface.

How HPHT Works:

• A small diamond seed is placed in a chamber with pure carbon (usually graphite).

• The chamber is subjected to extreme pressure (1.5 million+ psi) and heat (up to 1,600°C).

• The carbon melts and begins to crystallise around the seed.

• Over a period of several days to weeks, a diamond is formed.

Key Features of HPHT Diamonds:

• Often used to grow yellow or blue diamonds (due to nitrogen or boron).

• Produces very high-quality colourless diamonds in larger sizes.

• Can sometimes leave slight metallic inclusions (visible only under magnification).

🧪 2. CVD: Chemical Vapour Deposition

CVD is a more modern, energy-efficient method, allowing for more precise control over a diamond’s purity and growth.

How CVD Works:

• A diamond seed (usually a flat plate) is placed in a vacuum chamber.

• The chamber is filled with hydrocarbon gases, like methane and hydrogen.

• These gases are activated using microwaves or lasers, breaking down the molecules.

• Carbon atoms settle onto the seed, growing the diamond layer by layer over several weeks.

Key Features of CVD Diamonds:

• Typically produce exceptionally clean diamonds with high clarity.

• Colourless CVD diamonds can be grown without metallic traces.

• May undergo post-growth treatments (e.g. HPHT annealing) to improve colour or remove brown tints.

Are HPHT or CVD Diamonds Better?

There’s no universal “better” method—each has its strengths. What matters more is the quality of the final diamond.

At Diamond Lab, we work with both HPHT and CVD suppliers and only select GIA- or IGI-certified stones of the highest quality.

How Long Does It Take to Grow a Lab Diamond?

A single lab diamond takes 2 to 6 weeks to grow, depending on size and method.

• A 1 carat diamond might grow in 10–14 days with HPHT

• Larger stones (2–5 carats) take longer, especially with CVD

• After growth, each diamond is cut, polished, and graded just like a mined diamond

Despite being faster than natural formation, the process still requires significant expertise, equipment, and precision.

Do Lab Diamonds Need to Be Treated After Growth?

Some lab diamonds—especially those grown via CVD—may undergo treatments such as:

• HPHT annealing to improve colour

• Irradiation (for coloured diamonds)

• Laser inscriptions for certification or identification

These treatments are industry standard and always disclosed on the diamond’s certificate.

Do You Know What Type Your Diamond Is?

Most IGI or GIA reports for lab diamonds will indicate the growth method used. You can find this in the “Growth Process” section:

• Grown by CVD method

• Grown by HPHT method

• Post-growth treated (if applicable)

💎 See how lab brilliance shines in our
👉 Bezel-Set Radiant Diamond Ring

Final Thoughts: Science Meets Sparkle

Understanding how lab grown diamonds are made helps demystify their beauty. These diamonds are not “fake” or “synthetic”—they’re genuine, high-performance gemstones crafted with precision and care.

Whether grown with HPHT or CVD, lab diamonds offer:

• The same brilliance and durability

• Lower environmental impact

• Better value for money

• Full traceability and ethical sourcing

Want to Choose the Perfect Lab Diamond?

Book a one-on-one consultation at Diamond Lab to explore options, compare certified stones, and create something uniquely yours—from timeless classics to bold custom pieces.

📍 Book a showroom or virtual consult