How To Tell If A Diamond Is Real

Of all the gemstones in the world, the diamond is still the most revered and desired. Visit any jeweler in the world and you will see that the most exquisite, coveted, and expensive pieces all have one thing in common, diamonds!

Of course, with the most classic and sought-after pieces of diamond jewelry in the world being a diamond engagement ring, it comes as no surprise that the industry for fake diamonds is just as booming and busy as the industry for natural diamonds.

While synthetic diamonds and lab-created diamonds are viable alternatives for those who don’t have the budget for real mined diamonds, the deception of passing simulants such as moissanite and cubic zirconia off as the real thing is not only morally wrong but also illegal. It pays to have at least a base understanding of how you might be able to tell the difference between real stones and fake stones and you do not need to be a true diamond expert.

Before we look at ways to tell if your diamond is fake or real and how lab-grown diamonds affect the picture, you should know there is one way to guarantee the authenticity of a diamond. All diamonds sold by a reputable jewelry store will have a certificate from the GIA (Gemological Institute of America) or AGS (American Gemologist Society).

In the absence of a certificate, there are several tests to determine if your stone is a high-quality, authentic diamond.

Real Diamonds Vs. Lab Grown Diamonds

Although the industry is somewhat divided because lab-grown diamonds are produced synthetically and are not naturally mined, lab-grown diamonds are considered to be “real diamonds”. Lab-grown stones have the same physical properties as natural diamonds, have additional benefits, and cost less.

To “grow” a diamond, carbon atoms are extracted from high-pressure vapor in a special chamber in a process known as Chemical Vapor Deposition. For about three months, layer after layer is laid down until a fully formed diamond is produced.

It is impossible to tell the difference between a natural diamond and a lab-grown diamond with the naked eye. The only real difference is the atoms of nitrogen that are only visible under microscopic inspection. Otherwise, lab stones will react the same way as natural stones.

How To Tell If A Diamond Is Real

Most of these simple tests can only be performed on loose diamonds. When a diamond is in a piece of jewelry, the setting will obfuscate any results. Also, the metal surrounding the stone will have an impact. A yellow gold diamond ring for example may make the sparkle look different from the sparkle from a pair of white gold diamond earrings.

Check the Mount

It is unlikely that even the smallest carat diamond is going to be mounted in cheap material so the first and easiest test is to inspect the jewelry for its marks. Every piece of fine jewelry will be stamped with abbreviations that indicate the metal used. for example, the type of gold is shown by the K value (10, 14, 18, etc) while silver is indicated by a number that represents the parts per hundred (900, 925, 950, etc). Platinum is indicated by PT or Plat.

The Eye Test

We’re not suggesting you buy a jeweler’s loupe but if you have access to one, use it. When inspecting a mined diamond through a loupe you should be able to see any of its naturally occurring inclusions. These imperfections are completely normal. You may be lucky to have a flawless diamond but inclusions are an indication of genuine stones.

This test is not infallible. Lab-grown diamonds and cubic zirconia do not have inclusions because they are produced in sterile conditions. You’ll need to perform other tests for a definitive answer.

The Sandpaper Scratch Test

This is the most simple diamond test that you can perform. All it needs is some sandpaper and a bit of effort. Using the gritty side, rub the sandpaper against the stone. There should be no effect on your stone if it is a diamond because diamonds are the most complex natural material in the world. It helps to use a magnifying glass or loupe to search for scratches. If you notice any, then you can be sure that the stone is a fake.

The Read-Through Test

This test can only be performed on loose diamonds because when mounted in a piece of jewelry, the stone’s setting will be obstructive to the test. For this, you require a sheet of paper printed with some plain text. Newsprint is ideal.

Turn the diamond upside down and attempt to read the text. The determining factor is that the text will not be legible through a real diamond, but you will be able to see and make out all of the printed words on the paper with a fake diamond.

The Sparkle Test

The way that a loose stone can reflect and refract white light is always a good indication of whether or not it is real. A sparkle shimmer test can be very easily performed at home - you just need to see how the stone behaves underneath lights. It is impossible to alter the natural light refraction of a real stone. Even when there are any tiny inclusions real diamond light refraction is typically very uniform and accurate. Fake and synthetic stones sparkle much less than mined diamonds.

Look for shades of grey in a real stone. Natural diamonds have more greyish hues whereas there is always more iridescent sparkle in synthetic stones like cubic zirconia.

Things like moissanite, white sapphire, and white topaz will also react slightly differently under magnification. Importantly, the diamond sparkle light test can be applied to a mounted diamond just as easily as a loose diamond, which is useful for at-home tests with a piece of jewelry rather than a loose stone.

The Dot Test

Like the read-through test, the Dot test measures the clarity of something seen through the stone, and similarly, it is a test for loose stones. Draw a small dot in the middle of a blank piece of paper. Then place the stone flat side down on top of the drawn dot. If you can see a circular reflection of the dot, the stone is not a real diamond. A stone that does not refract light is not a true diamond.

The Water Test

For the water test, you need a glass of cold water. Drop your loose diamond into the glass of water, and if the stone sinks, you can be sure it is a real diamond. If it floats midway down the glass or comes up to the surface, then it is not a real diamond. The reason for this is that real diamonds have an incredibly high density, while fake diamonds do not.

The Heat Test

The heat test needs to be performed on a loose gemstone using an open but controlled flame (from a lighter, for example). Expose the stone to the flame for about 45 seconds, Be very careful with your fingers. A pair of tweezers with a rubber base is the best way to avoid burning. After 45 seconds, put the gemstone into a container of cold water.

Diamonds are very good conductors of heat, diffusing it throughout the stone, but fake diamonds are not able to withstand the heat. The shock of switching from extreme heat to sudden cold will ruin any type of stone that is not a real diamond.

The Fog Test

Another way to tell if your diamond is real is to place the stone in front of your mouth and fog it up with your breath like you would do a mirror or window. A fake stone will fog up for a few seconds. Real diamonds will not fog because their surface is naturally resistant to condensation. This is a test easily performed on stones in a piece of jewelry.

Thermal Conductivity Test

One final test that can be performed by a diamond tester is a thermal conductivity test. This is when heat is passed through a diamond to examine how fast the process occurs. Though diamonds conduct heat at the same rate as something like moissanite, moissanite is also an electric conductor whilst diamonds are not, so this is another key difference.

The Light Test

For this test, you need a source of UV light or black light. It is one of the least reliable tests so you shouldn’t rely on the results but it will back up any of the other tests above.

Under UV light, most real diamonds will show blue fluorescence. The issue is that the lack of blue fluorescence doesn’t equally fake. Fake diamonds can be made to give off blue fluorescence and some true diamonds simply fluoresce in different colors.

Know for Sure

These tests work well but the best way to ascertain if you have a real diamond is to get it authenticated by an appraising jeweler or gemologist. A professional diamond tester will have laboratory methods and tools that you will not have access to. They will also be able to test mounted stones more easily than any home test can.