Once you dip a toe into all the potential ways a diamond purchase can go wrong, it can become quite daunting. How do you know you are getting a real diamond? Can you trust the vendor? What if they were tricked or genuinely believed the stone is real? It does not help that many of the tests bandied about as proof of authenticity are bogus, or not as helpful as they could be! Let us take a look at these.
The Water Test
Drop a diamond into a glass three-quarter’s full of water, this test goes (and for some reason it is always ‘three-quarters’ not half, or completely full), and see if the stone falls quickly through the water or wafts down slowly. This is because diamond is denser than water, the explanation goes. But most stones are denser than water and only some kinds of glass will float or fall slowly through water – so all you will have established is that your stone is not a specific type of glass! Cubic zirconia – one of the more common diamond substitutes – is actually heavier than diamond!
The Heat Test
Now, there is a genuine heat for diamonds (detailed below) but this one is dangerous and will potentially ruin the value of your perfectly good diamond! The test says to take a glass of cold water, and an open flame of some kind. Hold your diamond in the flame for thirty seconds or so, and then plunge it immediately into the water. Diamonds are very heat conductive, the explanation runs, and real diamond will survive, while fakes will shatter. However, heating your diamond in an open flame can give it an ugly milky surface, killing the sparkle and ruining its value. And the fake that shatters or cracks could well be an attractive enough stone with some value in its own right, until it is broken and rendered worthless.
The Breath Test
Diamonds are not meant to ‘fog up’ like glass, so breathing on a diamond should not leave a foggy residue for longer than a split second. However, this only works on very large stones and unmounted stones – which removes a great many stones from being able to use this test!
Technology to the Rescue
It is neither dramatic nor exciting, but using a diamond tester is probably your best bet. Most fake diamonds are cubic zirconia, as mentioned above, or synthetic moissanite. As a side note, natural moissanite does exist, and if a large and beautiful example were to be found, it would probably be much more valuable than a diamond of a similar size due to its immense rarity.
Many of the characteristics of diamonds are shared by these two stones: they all sparkle beautifully, they are all denser than water, and moissanite can conduct electricity the same way that diamonds can.
Thus, if a stone is suspected to be cubic zirconia, it would only need to be subject to a thermal test to prove whether it is diamond or not, while moissanite will need the electrical current test, in which the stone is tested to see if a current will flow through it or not.
Unlike the dramatic open flame and cold water plunge mentioned above, this thermal conductivity test uses a finely calibrated instrument that applies a small amount of heat to the stone, and then sees how rapidly it dissipates to determine whether you are dealing with cubic zirconia or diamond.
If you are in any doubt about a stone’s make-up, it is always best to consult an expert jeweler you can trust, or do your research online yourself using a trusted independent source like Pricescope diamond forum by going on their how to tell if a diamond is real guide to get an impartial advice.
An excellent rule to follow is to always purchase GIA or AGS certified diamonds: you may not have personal access to the technology needed to verify a diamond’s authenticity, but they do!