Is that Bling the real thing? Use these 3 simple tests to help determine if it is a real diamond or an imitation.

The Fog Test

What to do: Breathe on the stone to try to fog it up like you would a window. If it stays fogged for a couple seconds, it’s probably a fake. 

How does it work: Diamonds are very good at conducting heat, so when you breathe on the surface of a real diamond it cannot retain the heat and therefore will not hold condensation. Quartz, glass and synthetic stones retain heat for a period of time and therefore will stay foggy for a brief period of time clearing up. Beware! A synthetic stone called moissanite closely mimics the properties of a diamond and so will also pass this test.


If it is too good to be true, then beware

What to do: Use some form of magnifying glass, jewellery loupe or microscope to examine the stone. If there are no inclusions (ie. is the stone flawless) then it may be a fake diamond, unless of course the person who gave it to you has deep pockets! 

How does it work: Inclusions are formed by small amounts of other minerals caught in the diamond when it was formed. They can take many forms:

  • Clouds
  • Feathers
  • Included crystals or minerals
  • Knots
  • Cavities
  • Cleavage
  • Bearding
  • Internal graining
  • Pinpoint
  • Laser Lines

Synthetic diamonds (such as cubic zirconia and moissanite) and quartz will not have inclusions. As natural Flawless Diamonds are very expensive, most diamonds you see have some form of inclusions. The greater the number and size of the inclusions, the more affordable the diamond. Although there are many other factors that affect the price of a diamond as well. So have a close look, and if it looks too good to be true, and your partner is not the high roller type, then it just may be a fake. 


Is that mount cheap or fitting for a diamond?

What to do: It is unlikely that a real diamond, in particular larger stones, will be set with a cheap metal. So look for the stamps on the jewellery to indicate if it is real gold or platinum. If it is set in a cheap metal or has CZ stamped in it, then alarm bells should be ringing!

What to look for:


Gold purity is measured in Karats (Carats), the ones below being the most common. (See out info page All About Gold for more information) 

  • 9K, 9ct or 375
  • 10K, 10ct or 416
  • 12K, 12ct or 500
  • 14K, 14ct or 585
  • 15K, 15ct or 625
  • 18K, 18ct or 750


Platinum is marked with the percentage of platinum contained in the metal as follows:

  • 850 (85% pure)
  • 900 (90% pure)
  • 950 (95% pure)
  • 999 (99.9% pure)

One sure sign is if has "C.Z." stamped on it, which means that the centre stone is a Cubic Zirconia, which is a synthetic diamond.

These steps are simple indicator tests that you can do at home, however, remember that the only way to be sure is for the diamond to be graded by a professional jeweller!