In this article you'll find an easy guide to telling a Diamond apart from other stones and imitations, with a few checks you can do at home.

A Diamond is a Diamond, whether it grew deep in the earth over millions of years or in a lab. A fake is something else: another stone that only looks like a Diamond, with a different composition. Here is what our jewelers look at, and what you can check yourself.

A lab-grown Diamond is a real Diamond

A Diamond is pure carbon arranged in a crystal, which is what makes it the hardest of all precious stones. A lab-grown Diamond has exactly the same composition, hardness and sparkle as a mined one. The only difference is how it was formed. Even a jeweler can't tell them apart by eye, and only a gem lab with specialised equipment can say where a Diamond comes from.

For our own collections we choose lab-grown Diamonds, so that no new stones have to be mined for our pieces.

What is a fake Diamond

A fake Diamond is a stone or a piece of glass, therefore it's made of a different material, chosen because it looks like a Diamond. These are the most common:

• Cubic Zirconia (8 Mohs): a crystal made in a lab, softer than a Diamond and with a more rainbow-colored sparkle.
• Moissanite (9,25 Mohs): a beautiful stone in its own right, with an even more colorful sparkle. It can fool simple testers.
• White Sapphire (9 Mohs): a real precious stone, with a softer and quieter shine.
• Glass (around 5,5 Mohs): it scratches easily, and its edges become rounded with wear.

What you can check at home

None of these checks is proof on its own, but together they give you good clues.

1. Breathe on it: fog clears from a Diamond in a second or two, because it spreads heat quickly. On glass or Cubic Zirconia, it lingers for longer.
2. Look at the sparkle: in daylight, a Diamond flashes white and grey with touches of color. Strong rainbow flashes point to Cubic Zirconia or Moissanite, and a dull shine points to glass.
3. Look closely: under a magnifying loupe, the facets of a Diamond meet in crisp, sharp edges. Glass shows scratches, rounded edges and sometimes tiny air bubbles. Small natural marks inside the stone, called inclusions, are normal in both mined and lab-grown Diamonds.
4. Read through it: you can try this if you have the stone and it's not set in a ring or another piece of jewelry. Place it upside down on a printed page. Through a Diamond, the letters blur and can't be read.
5. Certificates: in the case of large Diamonds or if they have a rare cut, you might consider asking for a certificate.

Skip the scratch test

You may have heard that a real Diamond scratches glass. It does, but so can Sapphire, Moissanite and even quartz, so the test tells you very little and it can chip your stone. A Diamond resists scratches like nothing else, yet a sharp knock at the wrong angle can still damage it.

Still in doubt?

If you're still unsure, you can always ask a jeweler. Have a stone you inherited or found in a drawer? Bring it to our atelier in Chiado or LX Factory, and our team will be happy to have a look.

Thinking of a piece with a Diamond, like an engagement ring? We design and make custom pieces in recycled Gold and Silver, with old or new gems, and can make your idea come to life.