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Expert Advice

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How to detect imitation diamonds

Technologies to produce imitation diamonds are becoming so sophisticated, that buyers of diamond jewellery should be alert. Here’s how to detect a fake diamond.

Diamonds are valuable, which makes it attractive to pass off imitation diamonds as the genuine article. Throughout history, glass, crystal and a range of gemstones have been presented as real diamonds. The boom in online trading has created whole new opportunities to sell imitation diamonds as real diamonds, while at the same time scientific developments have produced techniques to create imitations that are very hard to tell apart from real diamonds.

Crystal rhinestones, such as those produced by brands like Swarovski, have long been popular as a cheaper alternative to diamonds used on costumes, apparel and jewellery. Also sold as ‘diamante’, rhinestones are a diamond substitute made from rock crystal, glass or acrylic. The technique was developed in 1775 by the Alsatian jeweller Georg Friedrich Strass, who coated the lower side of glass imitation diamonds with metal powder.

Synthetic diamonds are man-made diamonds or lab-created diamonds with the exact same properties as a natural diamond. There are 2 types of lab-grown diamonds – High Pressure High Temperature (HPHT) and Chemical Vapour Deposition (CVD). The HPHT process mimics the geological conditions that create natural diamonds. It grows diamond layers on a diamond seed by subjecting carbon to high pressure and high temperature.

The CVD method is a revolutionary process that is the exact opposite of HPHT. Instead of pressuring carbon into diamond, the carbon is freed to become pure diamond. Moderate heat is applied to a carbon cloud in a vacuum chamber causing diamond atoms to rain onto and grow a diamond seed.

Synthetic diamonds are mainly used for industrial purposes. Although they appear very similar to natural diamonds, these must not be confused as synthetic diamonds are less valuable both emotionally and economically.

Lab-grown diamonds are not to be confused with simulants (diamond imitations), such as Cubic Zirconia (CZ) and Moissanite.

Finding out the difference between a genuine diamond and an imitation diamond sometimes requires expert knowledge. Moissanite can pass one of the simplest specialist tests to prove whether a diamond is real, thermal conductance testing. Cubic Zirconias have a similar refraction index to diamonds, as well as high dispersion, which means that jewellery with these diamond substitutes has a sparkle much akin to real diamonds.

Although many diamond related websites will tell you that you can tell your Cubic Zirconia and Moissanite from genuine diamonds by comparing them closely, this is not always possible when you buy diamond jewellery.

Take the difference in weight, for example, between a Cubic Zirconia and a diamond. A Cubic Zirconia weighs about 55 per cent more than a diamond of the same size. Similarly, a Moissanite weighs about 15 per cent less than a diamond of the same size. Great to know, but you are hardly likely to see the stone out of its setting or use scales to weight it when you go shopping for diamond rings.

If you have already bought the ring and really want to know whether the stone is a diamond or not, there are luckily some simple tests that may indicate fake diamonds. You could try placing the diamond on top of a newspaper or any other piece of paper with text or lines on it. Most genuine diamonds make it impossible to see through them due to their high refractive index, i.e. they reflect the light rather than for light to go all the way through them. Be careful though, as cubic zirconium oxide, synthetic rutile, fabulite and certain doublets escape this rule.

A CZ has a higher light dispersion than a diamond, meaning that it sparkles more than a diamond of the same size. Another simple test is to stick the stone in your mouth and exhale to create vapour. A fake diamond is likely to stay “steamed up” for more than three seconds.

You probably know that diamonds form one of the hardest substances known to man. A genuine diamond will scratch a piece of glass, where a fake will not. A real diamond won’t be scratched if you run it over a piece of sandpaper either. Unfortunately, quartz can look similar to diamonds and will also scratch glass. Only a real diamond can scratch another diamond though, but this is probably a test you will be reluctant to try out with your own jewellery.

The vast majority of diamonds have internal and external inclusions, tiny flaws that are unique to each individual stone. Most fake diamonds are absolutely clear.

The price can be a good indication of whether you are buying fake diamonds or not. If the price or discount seems too good to be true, it probably is. Unfortunately, the Internet is full of fraudsters only too happy to sell you imitation diamonds for the price of real ones, so buying through online auction sites can be risky.

At Vashi.com we examine every single loose diamond individually and provide a valuation certificate backed up with a money back guarantee. We know the inside-outs of every diamond we sell. Our engagement ring and diamond experts will be delighted to give you more tips on how to detect imitation diamonds and they are available for live chat (online, on the phone or in person) 7 days a week.You can also email us on service@vashi.com