Diamond Test: How to Tell if a Diamond is Real. Fake VS Real

Diamonds are precious stones and are even more adorable when gifted to a loved one. No wonder A-list celebrities are paying top dollar to buy them.

But here is the problem associated with purchasing rare gems: the untrained eye cannot differentiate fake diamond jewellery from the real deal. 

And if you are not careful, scammers can sell you ordinary zirconia crystals for the price of a genuine diamond rock.

But how can you tell if a diamond is real?

Through our years of experience in the diamond jewellery trade, we have mastered how to tell a real diamond from a fake one. Some of these techniques can be carried out using homemade tools like a simple water bath, while others require expert help. 

So, let’s go through some famous diamond identification tests used to determine if a diamond is real or not.

The most common test to determine if a diamond is real is by running ultraviolet light through it, specifically black light. This UV diamond test is not always definitive, depending on the type of diamond. However, expert gem dealers can use it to confirm the authenticity of a real or fake diamond.

What do you need for testing

As mentioned earlier, you need a UV light source to verify if the diamond is real. You also need a stable non-reflective platform on which to place the stone.

How to test

To test the diamond, you need to find a completely dark room and expose it to the ultraviolet light source. Then, hold up the rock to the light and observe.

Results meaning

If the diamond gem displays a blue glow under UV light, then the diamond is real. If the stone does not react to the light, the stone is probably fake.Note that other diamond cuts can emit green and yellowish colors, depending on their level of purity.

The heat (thermal conductivity) test is also a great way to determine if the diamond is real. This test uses the known physical and chemical properties of diamond stones to differentiate fake diamond from real gems.

What do you need for testing

For this procedure, you need a hand-held diamond tester. They are quite cheap online.

How to test

Before starting the test, make sure that the gem is free of external impurities that might provide a layer of coating. If you don’t clean the gem, the coating will affect the results.

Results meaning

If the diamond tester displays a positive heat check result, the diamond is real. Else, the gem is probably a knockoff.

Caveat: Diamond gems and moissanite stones have similar thermal conductivity. So, you might still need extra expert consultation.

In the past, the scratch test was the widespread method to determine real diamond vs fake diamond stones. Although other advanced tests are now available, you can still use this technique to determine if the diamond is real.

What you need for testing

The scratch test requires a plain and flat mirror.

How to test

For those who don’t know how to tell if a diamond is real, simply grab the gemstone and scrape it along the mirror’s surface a few times.

Results meaning

If scratches appear on the stone or the mirror’s surface, the gem is a fake diamond. Otherwise, the diamond is real.

Caveat: Materials like cubic zirconia have the same hardness as diamond. So, the scratch test might give the same results for both diamond and cubic zirconia.

The water test is a quickfire test within home conditions. This test is not conclusive by any means, but you can use it to spot fake diamond gems asap.

What you need for testing

You need a bowl of water. Don’t forget to isolate the diamond gem from the metal framework.

How to test

Fill the bowl halfway and drop the gem in the half-filled bowl. Make sure that the water is clean and doesn’t contain other solvents.

Results meaning

Diamond is denser than water, which means that any gem that doesn’t sink is a fake diamond stone. Otherwise, the diamond is real.

The fog test also relies on the diamond gem’s excellent thermal conductivity. All you need to do is breathe on the stone and wait a few seconds to identify if the diamond is real.

What you need for testing

You only need air from your lungs.

How to test

Firstly, clean the gem to eliminate all impurities. Hold up the stone to your mouth and blow. Track the amount of time it takes for the ‘fog’ to clear.

Results meaning

If the fog clears within 3 seconds, then the diamond is real. If the fog doesn’t clear within 3 seconds, then you have a fake diamond in your hands.

This test relies on your visual perception to spot a fake diamond. You only need to observe the gem’s refractive index and how it reacts to a bright light source.

What you need for testing

You need a bright light source for the sparkle test.

How to test

Put the stone up to the bright light and observe the sparkles.

Results meaning

If the diamond is real, you will observe a wide range of brilliance and light dispersion from the gem. Else, the diamond is fake.

The dot test (or newspaper test) is used to determine if a diamond is real or just a fake diamond gem.

You only need to draw a dot on a newspaper and observe it through the gem. If you have a loose stone, this is how to tell if it’s a real diamond or a counterfeit jewel.

What you need for testing

You need a newspaper or a clear piece of paper with a small dot placed on it.

How to test

Place the stone on the paper and observe the dot through the gem.

Results meaning

The diamond is real if the gem refracts the dot, making it impossible to read. If you can see the dot through the rock, then you have a fake diamond gem.

You can tell if a diamond is real with a chart and a specialised carat-weighing scale. The readings on the chart will show you how to tell if it’s a diamond or a different stone altogether.

What you need for testing

You need a specialised scale and a standard chart to test if the diamond is real.

How to test

Clean the surface of the scale. Then, place the stone on the scale and take the measurements.

Results meaning

If the readings on the scale don’t match the standard figures on the chart, you probably have a fake diamond gem.

Caveat: You need a fine-tuned scale to spot a fake diamond. If you don’t want to spend money on these scales, you can delegate the testing to experts.

According to the GIA, round diamonds have cut grading, other shapes graded for symmetry and polish. So, your gem should always fall within one of these shape categories if the diamond is real.

What you need for testing

You need a standard diamond identification chart and a magnifying glass.

How to test

Watch the edges and facets to determine the diamond’s cut shape.

Results meaning

If the cut doesn’t match any standard category, that’s probably a fake diamond.

Experts can spot original diamonds using standard clarity tests and X-ray technology. Unfortunately, the heavy-duty machinery needed for this test is not readily available to those who want to test diamond jewels at home.

So, how can you tell a real diamond from a fake diamond without X-ray machines?

Just look at the gem through a microscope or magnifying glass to see if the diamond is real.

What you need for testing

You need a magnifying glass or microscope.

How to test

Make sure that the gem is clean and dry. View it through a microscope.

Results meaning

If you spot impurities in the gem, then the diamond is real. If the impurities appear in the form of bubbles, there is a high probability that you have a fake diamond.

Caveat: Actually some types of inclusions can seem to be a bulb. Some diamond gems might not contain imperfections. So, you still need other tests to make sure that the diamond is real. 

Testing diamonds for authenticity is a painstaking task. But if done well, you will rest assured that your diamond is real. Use any of the techniques above to verify if you have a fake diamond gem or the real thing.

If you don’t want to go through the hassle of checking for real and fake diamonds jewellery, we have got you covered. Our experts at GS Diamonds will guide you through the purchase and verification to make sure you get the value for your money. Reach out to us right away for consultations.