How to Check if Your Diamond Is Real

Est. Reading: 3 minutes
November 23, 2023
a stylish businessman holding up a large diamond in front of his face
Table of Contents

When it comes to buying diamonds, most people tend to focus on the all-important “4 Cs” - cut, colour, clarity, and carat. These 4Cs are regarded as the main method used to determine the individual value of a diamond. As well as that, they can also be helpful in comparing prices of diamonds between different jewellers.

Although these 4Cs are important, it can be extremely easy to get lost in the small details.

Whether you’re thinking about a diamond ring for an engagement, or you’ve recently come into possession of a precious diamond family heirloom though, it’s also important to also question the authenticity of your diamonds.

Diamonds – “Real” vs. “Fake”

In most cases, “fake” diamonds are simply gemstones that have been mistaken for real diamonds.

For those unfamiliar with a diamond’s structure and components, it can be very easy to mistake a diamond with other gemstones such as cubic zirconia, moissanite, white topaz, or white sapphire.

If you’re questioning the authenticity of a diamond, then the only way to know with absolute certainty, is to have it professionally appraised by a reputable jeweller.

However, if you're in a hurry, here are few easy tests that you also can use at home:

1. Drop the loose diamond in water.

If your diamond isn’t set in a jewellery piece, then simply drop the stone into a glass full of water.

If it is in fact a real diamond, it will drop to the bottom of the glass due to the high density and weight of the stone. Fake diamonds on the other hand, will usually float near the top, or only fall towards the middle of the glass.

2. Check the jewellery mount.

If your diamond is already mounted, then the jewellery piece itself can give some clues as to the likelihood of it being authentic or not.

In general, diamonds are only set in high-quality jewellery made of platinum, white gold, or yellow gold. By searching for inscribed markings on the metal such as “PT” (platinum), or “10K”, “14K” and “18K” (for gold), the probability of it being a true diamond is already quite high.

On the other hand, if the markings indicate “C.Z” (cubic zirconia) or “.925” (for sterling silver), it’s very likely that the stone is not a real diamond.

3. Breathe on it.

One quick and easy way to determine if your gem is a real diamond is the “Fog Test”.

Simply breathe on the stone as if you were trying to fog up a window or clean your glasses – if the surface of the stone stays fogged up with moisture, then it’s likely not a real diamond.
If the stone doesn’t fog up, it has a higher likelihood of being a real diamond – this is because water can’t easily condense on the surface of a real diamond.

How to Check a Diamond While Shopping

If you’re shopping for a diamond, then you likely won’t be able to perform these tests. Instead, always be sure that you only buy diamonds from a reputable dealer with a good return policy.

If the diamond doesn’t have a grade report from a gem laboratory (such as GIA), ask if they’ll send it to the lab for you – for a real diamond and a reliable seller, this shouldn’t be an issue.

Bonus: How Do Jewellers Check if Diamonds Are Real or Not?

Jewellers use a various way of checking whether a diamond is real or not. In the video below you can see how we check our diamonds. Real diamonds show up as a lovely blue where non-diamonds do not.

Need Help from the Professionals?

At Martin Gear Jewellers, we’ve been both manufacturing and appraising diamond jewellery for decades. To learn more, simply contact us or drop into our store on 5 Mary St, Dublin 1

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