A jewelry expert has revealed the easy tests you can do at home to check if diamonds are real and avoid being scammed by convincing fakes this Christmas.

Sarah Fielding from Infinity Diamond Jewellery outlined how you can use ordinary household items to check if a diamond is real before spending thousands of pounds on what could turn out to be worthless glass.

The expert explained that the unique physical properties of diamonds can help identify real ones and spot fakes that often fool shoppers.

The Fog Test

The fog test is one of the quickest ways to check if your diamond is genuine. Just breathe on the stone as if you’re fogging up a mirror. A real diamond will clear almost instantly because diamonds are excellent heat conductors, while fakes stay foggy much longer.

The Water Test

The expert added that another reliable test uses a glass of water to check for authenticity. Drop the stone into a glass of water, and as real diamonds have high density, a genuine one will sink straight to the bottom. Most fakes will float or sink slowly.

The Newspaper Test

The third test Fielding recommends involves using an everyday newspaper. Place the stone on the paper and look through it. If you can read the text, even if it’s blurry, it’s likely not a diamond. Real diamonds refract light so effectively that you shouldn’t be able to see through them at all.

The Sparkle Test

Fielding added that this test can be performed anywhere with good lighting, like sunlight or under a strong lamp. In a well-lit room, a genuine diamond will have a crisp, strong sparkle with colourless light. Fakes often show rainbow colours and more subdued sparkle, giving it a glassy look instead of the diamond’s crisp brilliance.

Get an Electronic Diamond Tester

For those willing to spend a small amount, Fielding suggests buying an inexpensive electronic tester. Diamond testers now cost as little as £20 online and measure thermal conductivity, a property that distinguishes real diamonds from fakes.

Check Settings and Certificates

The expert also warned buyers to check for tell-tale signs of fakery in settings and certificates. Genuine diamonds are rarely set in cheap metals, so look for hallmarks indicating gold, platinum or silver.

Make sure any certificates you received with diamonds have been issued by reputable laboratories and contain a unique identification number. Scammers often forge these documents, so always verify certificate numbers with the issuing authority.

Her advice comes as a UK court shut down two connected companies for misleading investors by inflating the value of fancy coloured diamonds sold as investments.

One company ran a high-markup diamond sales scheme through UK brokers, while the other issued fake valuation certificates without ever actually examining the diamonds, artificially boosting their grades and prices. The court heard diamonds were sold with mark-ups between 220% and 745%, making it impossible for buyers to ever recover their investment.