What Is a Lab-Grown Diamond?

Short answer: A lab-grown diamond is a real diamond, grown in a laboratory by recreating the conditions that form diamonds in nature. Its chemical structure, hardness and light are identical to a mined diamond. The only thing that sets it apart is its origin: a controlled growth that takes weeks instead of an underground process that takes millions of years.

Is a lab-grown diamond a real diamond?

Yes. If we define “real” the way gemology does: what makes a diamond a diamond is carbon atoms arranged in a specific crystal structure. A stone grown in a laboratory has exactly the same structure. That is why it has the same hardness, the same thermal conductivity and refracts light in exactly the same way.

This table shows that a lab-grown diamond is not a “look-alike” stone. Cubic zirconia or moissanite resemble diamond but are not diamond; we explain that difference further down.

How is it grown? CVD and HPHT

Lab-grown diamonds are produced by two main methods. Both grow new diamond crystal on a thin diamond “seed”.

CVD (chemical vapour deposition)

In a vacuum chamber, a carbon-rich gas mixture (usually methane and hydrogen) is turned into plasma with microwave energy. Carbon atoms released from the gas settle on the diamond seed layer by layer. Growth takes several weeks. Some stones receive an additional treatment after growth to improve their colour; this is stated on the stone’s grading report.

HPHT (high pressure, high temperature)

The conditions deep inside the earth are recreated. Under pressure tens of thousands of times higher than the atmosphere and at temperatures above 1,300 °C, a carbon source crystallises as diamond on the seed inside a molten metal solvent.

Both methods produce stones of excellent quality. The method alone says nothing about quality. What matters is the stone’s cut, colour and clarity grades.

How does it differ from a mined diamond?

In appearance, durability and light there is no difference. The real differences are these:

• Origin: A mined diamond forms deep underground over millions of years. A lab-grown diamond is grown in a controlled environment within weeks.
• Price: A lab-grown diamond of the same carat, colour and clarity is noticeably more affordable than its mined counterpart.
• Resale value: A mined diamond holds its value relatively well. The resale value of a lab-grown diamond is low.
• Identification: The two cannot be told apart with the naked eye. The difference is detected in gemological laboratories with special instruments that read the stone’s growth marks.

A large share of lab-grown diamonds are of “Type IIa” purity: a chemically very pure type of diamond containing almost no nitrogen, found in only a small fraction of mined diamonds.

Synthetic, artificial, imitation: what does each mean?

These words are often confused, and the confusion is the biggest obstacle to buying wisely:

• Lab-grown diamond: A real diamond. In gemological language “synthetic diamond” means the same thing. Synthetic here does not mean fake; it means “grown by human hands”.
• Imitation (simulant) stones: Stones that look like diamond but are not diamond. The best known are cubic zirconia and moissanite. Their chemistry, hardness and light are different.

In everyday speech “artificial diamond” is sometimes used for lab-grown diamonds and sometimes for imitation stones. The way to be sure what a stone is, is a report issued by an independent laboratory.

How is it graded? The 4Cs and the certificate

A lab-grown diamond is graded by the same four criteria as a mined diamond:

• Carat: The weight of the stone (1 carat = 0.2 grams).
• Cut: The stone’s proportions, symmetry and polish; these decide how light enters and leaves the stone.
• Colour: A scale starting at D (colourless) and moving towards yellow.
• Clarity: How visible internal and external imperfections are.

Independent gemological laboratories such as IGI issue separate reports for lab-grown diamonds. The report clearly states that the stone was grown in a laboratory. The report number is usually laser-inscribed on the stone’s girdle (its widest edge) and can be checked on the laboratory’s website. Always ask to see the report and this number before buying a stone.

What determines the price?

Price does not depend on carat alone. Between two stones of the same carat, differences in cut, colour and clarity create a serious difference in price. Price does not rise in proportion to carat either; it jumps at thresholds such as 1, 1.5 and 2 carats. The total price of a stone set in a mount is further determined by the metal (gold purity), side stones and workmanship.

Our advice for using your budget well:

• Never compromise on cut quality.
• Relax colour and clarity to the grade where no difference is visible when worn.
• Consider weights just below a threshold.

Durability and care

A lab-grown diamond has the same hardness as diamond, the hardest known natural material. It is suitable for everyday wear, does not scratch, does not dull over time and does not change colour. What makes a stone look dull is usually the oil and dirt that collect on it. Cleaned with warm water, a few drops of dish soap and a soft toothbrush, it returns to its first-day light. We recommend having the prongs (the parts that hold the stone) checked by a jeweller once a year.

Who is it the right choice for?

A lab-grown diamond is a strong choice for anyone who wants to spend their budget on visible beauty. With the same budget you can reach a larger, better cut or whiter stone. The fact that no mining is involved is also an important reason for many people.

If you plan to resell a stone for its value one day or keep it as an investment, a mined diamond may suit you better. We say this openly, because the right choice can only be made with the right information.

Frequently asked questions

Can a jeweller tell a lab-grown diamond apart?

Not with the naked eye or a jeweller’s loupe. Special instruments in gemological laboratories can identify the origin from the stone’s growth marks. That is why a lab-grown diamond should always be sold with a clear statement of what it is.

Does a lab-grown diamond tarnish or change colour?

No. Because it is a diamond, it does not tarnish and its colour does not change. If it looks dull, it is dirt and oil on the surface; cleaning brings the light back.

What is the difference between a lab-grown diamond and cubic zirconia?

Cubic zirconia is a stone that looks like diamond but is not diamond. It is softer, scratches and clouds over time, and refracts light differently. A lab-grown diamond is a real diamond.

Which method is better, CVD or HPHT?

Both can produce high-quality stones. A stone’s value is determined not by the method but by the cut, colour and clarity grades on its report.