Is it Fake or Real?

Whilst there is no substitute for taking what you believe to be a diamond to a diamond expert or jeweller for confirmation, there are some tests you can do at home to see if the diamond you have is real or laboratory created.

Diamond Simulants

Some of the most common fake diamonds, or diamond simulants are hard, flawless and have no colour.

Synthetic moissanite is currently the most convincing false diamond. It has a brilliance and fire similar to a diamond, and is the hardest diamond simulant so far since it can pass many home tests for an authentic diamond. Test for moissanite using a loupe where you can see doubling images appear inside.

Other diamond simulants include yttrium aluminium garnet, gadolinium gallium garnet, zircon, synthetic rutile and synthetic titanite.

Synthetic diamonds are man-made diamonds created in laboratories. These are not fake diamonds and are almost impossible to distinguish from natural diamonds.

Ask the experts

A professional diamond expert will be able to tell you if a diamond is real or not since they have access to a range of specialist equipment. First they will look at the diamond under magnification, looking for defects. There are also conduction and other tests to confirm you have a genuine diamond. If it is an actual diamond they will be able to provide an authentication certificate.

A loupe, which is a 10x jeweller’s magnifying glass, will show up any imperfections on a stone. Fake diamonds, such as cubic zirconia or moissanite will not show any blemishes or inclusions when examined under a loupe. All diamonds have inclusions and or blemishes and even the best quality diamonds will have some internal oddities that identify them as real. In comparison, most bogus diamonds are made to look totally perfect.

Experts will also be able to look for scratches and scuffs. A cubic zirconia, even a new one, will have some small abrasions that won’t be found on genuine diamonds. The real test is checking the edges of the stone. A real diamond will appear much sharper, because their hardness allows them to be cut with ultra-sharp edges. A synthetic stone will show scuff marks.


a diamond and a zirconia stone

Weight Test

Cubic zirconia weights about 55 per cent more than diamonds for the same configuration. Using a jewellers carat scale, you can see if the stone weighs much more in comparison to a genuine diamond of a similar size.

UV Light Test

Many diamonds glow blueish under ultraviolet light and your jeweller will have a high-powered UV light to test and demonstrate for diamond fluorescence. Almost all fake diamonds do not glow blue. If your stone shows a medium to strong blue, you have a diamond, though its value will be less than others that lack blue fluorescence. Diamonds with little or no flurorescence may be better quality diamonds.

Thermal Conductivity Probe

Diamond’s conduct electricity and jewellers can test loose stones for this. This is particularly useful in confirming if a stone is a diamond or moissanite, which when well made can be extremely difficult to tell apart from a genuine diamond. Moissanite will not conduct electricity with as much strength as a diamond, so most jewellers have a machine to test conductivity.

Home Tests

a diamond a uv light

Water Test

Drop a loose stone into a container of water. A real diamond has high density, so is expected to sink. If the stone floats just under or on the surface of the water, it is not a diamond.

Fog Test

Breathe on the stone if you were trying to mist up a mirror. If the fog lifts straight away the diamond is real, though there is a risk it could be a moissanite. If it takes a few seconds for the mist to disappear, its probably a fake. Oil and dirt on the stone can effect the reliability of this test and it is also inaccurate on stones that are not pure diamond but combined with another element such as a diamond simulant like CZ.

Heat the Stone

This test will destroy a stone that is not a diamond. Glass, quartz or cubic zirconium will shatter. Diamonds do not react to high heat so will survive. Heat the stone over a flame for 30 seconds and then immediately drop the stone into a glass of cold water. A real diamond will show no reaction.

Transparency Test

Find a newspaper or book with lots of lettering. Place the stone flat side down onto the letters. If you can read the letters of the newspaper the diamond is fake. A real diamond will refract light in different directions so intensely, you will not be able to see through it. It is worth checking the diamond as some that are cut shallow can be read through.