Suspicion over the authenticity of a newly bought diamond is one of the most common things felt by jewelry customers. The best and safest way to be sure in this regard is to stick to certified stones, which abound in the diamond industry. You can search for a variety of loose stones online which, if legitimate, will come with a GIA and/or IGI certification.
However, this option is not always open; for instance, you may have come by a jewelry piece as your inheritance, in which case, there are few ways of knowing what you have in your hand is a genuine piece. Specifically, there are seven reliable ways to make sure, and these are detailed below.
You would need a 10x magnifying glass, the stone you need to check, and another stone that you know for certain is a natural diamond. Now observe the dubious gem under the magnifying glass. After this, look at the diamond you are certain about, and note the differences. The second stone would no doubt have flaws, such as internal inclusions or external chips.
If the stone you are checking is moissanite or CZ, chances are that you will not spot a single structural flaw. Real diamonds are naturally formed, and CZ and moissanite are cultured in labs. The latter never endure the exact same environmental pressures, and their too-perfect appearance would testify to that.
Take the stone to a cool location and blow on it. This is to surround the stone with relatively hot and moist air. A real diamond would expel this heat in a jiffy, which means that you would not see any surface fogging. If you are holding a fake diamond or a simulant though, this effect will occur at least to some degree.
The Black Light Test
For this, you would need a strong UV light. Hold the stone under this light and check for any color change. If you see a bluish glow that is otherwise absent, it means that what you are looking at is a real diamond. The definitiveness of this test is not very high though; there are some rare real diamonds, which do not emit fluorescence under any condition.
Place the questionable stone over a newspaper and check if the words underneath are visible through it. If the diamond is real and of good quality, the light will be refracted intensely enough so that you cannot read through it. CZ, on the other hand, is much more transparent, which allows you to clearly see what is on the other side. Yet the main problem with this test is that it does not work on smaller stones, or those set into jewelry.
For this test, you would need a flame source, such as a candle or a lighter, a glass of really cold water, tweezers to grab the stone, and the stone you need to check for authenticity.
Using the tweezers, hold the stone over the flame and heat it for just over half a minute. After that, immediately drop it in hot water. A real natural diamond would not be affected by the drastically rapid change in temperature, because it would be too strong for that. Fake diamonds, meanwhile, would either shatter or break when the heat drops too quickly.
This test can assure you of the realness of your diamond, but at the cost of residual ash from the flame, which you would have to clean up later. The fastest way to clean a diamond is soaking the gem in a mix of toothpaste and warm water for a couple of minutes, and then scrubbing it with a soft-bristled toothbrush.
Get a glass of water and drop the stone into it. Loose diamonds are dense enough to instantly sink to the bottom, but fakes would generally either float or take their time sinking. This test is hardly foolproof because some stimulants of large size could sink just as rapidly as a real diamond, despite lacking the latter’s density.
This test is not one you can perform by yourself at home, because it requires specialized equipment and proper experience handling the same. You need to head to a local jeweler and request them to check the electrical conductivity of your stone. It is a lesser-known fact about natural diamonds that they resist the flow of electricity. Moissanite and other stimulants allow current to pass, so an electricity testing setup can resolve the matter of authenticity fairly quickly.
If you are in possession of a loose diamond or set stone that you wish to make sure is authentic, try the tests mentioned here which you can safely perform at home. If those do not satisfy you or if you want more substantial results, then get to a jeweler to do the conductivity test and determine whether your diamond is real.