How to Tell Diamonds Apart: Real, Lab-Grown or Imitation?

"Is the stone real?" is one of the most common questions about diamond jewellery. The answer depends on what you want to know: whether it is a diamond at all, or whether it comes from a lab or from the earth. Both can be told apart, but not with household tricks.

Diamond, lab-grown diamond, imitation: what is the difference?

• Natural diamond: Carbon that formed over very long periods deep in the earth under high pressure.
• Lab-grown diamond: Also a real diamond made of carbon, grown in a few weeks under controlled conditions. Chemically, physically and optically identical to a natural diamond.
• Imitation: A different material that looks like a diamond, such as cubic zirconia, moissanite or glass. It is not a diamond.

Why household tests don't work

Tests such as fogging the stone, the newspaper test, the scratch test or a glass of water sound practical but are unreliable. They cannot reliably tell good imitations from diamonds and, at worst, damage your jewellery. Don't use them.

What a diamond tester can and can't do

Simple diamond testers measure thermal conductivity. This reliably tells diamonds apart from cubic zirconia and glass. Some devices confuse moissanite with diamond unless they also measure electrical conductivity. A lab-grown diamond and a natural diamond give the same result on these devices, because they are physically identical.

How lab-grown and natural diamonds can be told apart

Only gemmological laboratories can determine this. They use special equipment, such as spectroscopy and fluorescence analysis, to examine the growth features of the stone. The difference cannot be seen with the naked eye or with a loupe.

That is why two things matter when you buy a diamond:

1. Certificate: An independent report, for example from IGI, states carat, cut, colour, clarity and whether the stone was grown in a lab.
2. Laser inscription: Many certified stones carry a microscopic inscription on the edge with the certificate number. It can be read under a loupe and clearly links the stone to the report.

Recognising moissanite and cubic zirconia

• Cubic zirconia: Heavier than a diamond of the same size, with very colourful sparkle and much less expensive.
• Moissanite: Stronger, rainbow-coloured fire and double refraction, which can show up under a loupe as doubled edges. It is a material of its own, not a diamond.

What to look for when buying

• The seller states clearly whether it is a lab-grown or a natural diamond.
• A certificate from a recognised laboratory is included.
• The details on carat, colour and clarity match the certificate.

All LUNEVYA diamonds are lab-grown diamonds with an IGI certificate. Read more about production and differences in our complete guide and in the article How Lab-Grown Diamonds Are Made.

Frequently asked questions

Is a lab-grown diamond a real diamond?

Yes. It is made of the same carbon and has the same crystal structure as a natural diamond. It is not an imitation.

Can a jeweller identify lab-grown diamonds?

Not with simple means. That takes a laboratory or special testing equipment.

Can I test my diamond myself?

You can have the certificate matched against the laser inscription. Leave everything else to a specialist laboratory.

Where can I find engagement rings with certified lab-grown diamonds?

In our EVYANA collection.