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Can Moissanite Pass a Diamond Tester?

So you’ve stumbled across moissanite: the mysterious gemstone that’s eco-friendly, conflict-free, as dazzling as a diamond, but significantly less expensive. As a more affordable and ethical choice of stone for an engagement ring, moissanite is undoubtedly the best diamond alternative on the market. However, can moissanite actually be passed off as a fake diamond? And could it go so far as to deceive a diamond tester? Read on to find out!

Moissanite is one of the rarest substances found in nature.

Since first being discovered by scientist Henry Moissan in a meteor crater, experts have been able to replicate this exquisite gemstone in a lab and offer it to the world as a masterfully crafted, socially-responsible, eternally brilliant gemstone. As more and more people discover moissanite, one of the first questions that cross their minds is “So, what’s the catch?”. It feels too good to be true – but it’s certainly not! Moissanite has a hardness rating of 9.25-9.5 and is a close second to diamond which ranks a 10. This means that moissanite is extremely durable and will last just as long as a diamond, maintaining its clarity, fire and brilliance for a lifetime. Because of this, and its incredibly similar appearance to a diamond, moissanite is sometimes used as a ‘fake diamond’ in engagement rings. Unless you know what to look for, it is extremely difficult to tell the difference between moissanite and diamond, even when placed side by side. So whilst your friends and family are unlikely to pick up on it, how can you actually tell the difference?


How to tell Moissanite from Diamond

When placed side-by-side, it is almost impossible to tell the difference between a same-sized Moissanite and Diamond. With the naked eye, a high-quality moissanite and diamond will be almost indistinguishable. Though very subtle, the main visible difference is moissanite’s greater brilliance. Compared to a diamond, moissanite is more sparkly and exhibits more colourful fire. This is due to moissanite’s higher refractive index and double refraction property. We won’t delve too far into the science behind it but, put simply, when a single beam of light enters the crown of a doubly refractive gemstone, two beams of light will exit. A singly refractive gemstone such as a diamond will see one beam of light enter and remain intact as it exits, unbroken. This is neither a good or bad thing, but simply comes down to the inherent crystal structure of the gemstone. Moissanite’s double refraction accounts for the higher dispersion of light – or, in other words, moissanite’s more colourful display of sparkles (fire). This heightened brilliance can create a “disco ball” effect as the light reflects out of the stone in rainbow flashes. Again, it is quite difficult to detect this difference in person but it will become more noticeable in larger stones, as more light is reflected and more colour is displayed. That being said, unless they know what they are looking for, this difference is unlikely to be observed by your friends or family.




Diamond Testing

To a trained professional, moissanite can usually be identified by its distinctive fire. However, this is not an exact science and some professional gemological equipment will be needed to truly tell the difference between a moissanite and diamond. This is where a diamond tester comes in. First introduced into the jewellery industry as a way to distinguish natural diamonds from cubic zirconia (a very common fake diamond), a diamond tester is used to test the heat conductivity of a gemstone. Since diamonds are known for being exceptional conductors of heat, this distinctive feature can be used to distinguish them from other gemstones or faux diamonds. By looking at the way heat moves through the stone, the tester can detect whether the stone is a diamond or not.

Can Moissanite Pass a Tester?

However, this method is not very effective when it is used to differentiate between moissanite and diamond. Unlike faux diamonds and other gemstones, moissanite is also an effective conductor of heat. For this reason, when using a diamond tester that detects thermal conductivity, moissanite will pass as a diamond. Basic diamond testers generally only test thermal conductivity, so though they will be able to tell your diamond or moissanite apart from other stones, they typically won’t be able to pick up the slight difference in conductivity between moissanite and diamonds. Though they are a valuable tool for jewellers and gemologists, basic diamond testers cannot be fully trusted to give an accurate reading. One thing to note is that lab-grown moissanite has only been in production since the 1990s so if your diamond is from an earlier era and it tests positive for diamond, you can be sure it is an authentic diamond.


So, How Can You Test Moissanite?

To find out the truth about your gemstone, you’ll need another kind of tester. Since moissanite is ever so slightly electrically conductive, specialised moissanite testers were developed. Seeing that diamonds are not electrically conductive, this method is able to accurately distinguish between a moissanite and diamond. Many of today’s diamond testers are multi-testers, meaning they will detect both the thermal and electrical conductivity of a gemstone in a single test.

If you are unsure of your diamond’s authenticity or would simply like to have your gemstone tested, unfortunately there aren’t any easy or reliable at-home methods to give you a reliable result. We would suggest taking your stone to a trained jeweller to be examined or having it analysed by a gemological laboratory.


So, can moissanite pass a diamond tester? In short, yes. And could it be passed off as a diamond? To the majority of people in your life, yes. If they don’t know what they’re looking for, moissanite can most certainly pass as a diamond if that is your intention. However, for it’s lasting beauty, extra sparkle and attractive price tag, we would argue that moissanite deserves to be appreciated and valued for its unique qualities. Regardless of whether you’re a moissanite lover or you’d like to use it as a diamond dupe, we’d love to help you learn more about this incredible gem and assist you in your journey to developing your dream ring!

Browse our range of exquisite engagement rings here and if you have any questions please feel free to contact us here.

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