How to Tell If Diamonds Are Real: DIY Methods to Try

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With look-alike diamond alternatives like cubic zirconia and moissanite readily available, it is crucial to know how to tell if diamonds are real. As with every business, fakes are abundant, and we wouldn’t want you to get conned.

We’ve found 12 of the best tests to discover whether your new diamond is real or fake. You can do most of these at home; no expertise needed. 

How to Tell If Diamonds Are Real (12 Methods)

Diamonds are the hardest known natural material formed in the earth’s upper mantle under heat and high pressure. They travel to the earth’s surface through volcanic eruptions, where they are available for mining. There are also diamonds made in the lab from pure crystallized carbon. These diamonds are also considered real, although not natural.

The DIY tests on our lists are quick and do not require expensive tools. Still, it’s worth knowing that they might be inconclusive. 

💡 Keep in Mind: The only way to know that your diamond is real is to visit a jeweler.

But, if you still want to try your hands at these tests, you’re welcome to do so. 

Water Test

Fill a glass cup ¾ with clean water. Drop your diamond in the water and observe what happens. If it sinks to the bottom entirely and immediately, your diamond is likely real, but if it floats on top, you’re holding a different gemstone. 

Diamond will sink because of its high density. While this test is easy, it cannot stand alone because other stones may act similarly to diamonds.

Fog Test

The fog test is one of the easiest and quickest ways to test your diamond. It only takes seconds. Pick up your diamond, clean it with a soft cloth to remove any oil or dirt, and then fog it with your breath. If it clears up in a second, your diamond is real, but if it stays for a few seconds, it’s likely not the real thing.

Fog on diamonds clears up fast because diamonds disperse heat quickly. If you have a genuine diamond, you can use it to compare your results as a standard for the test. 

Heat Test

For this test, you need a glass of cold water, a lighter, and fire-proof gloves. Heat the suspected diamond stone with the lighter and throw it immediately into the glass of cold water. If it shatters, it is a fake diamond, but if you do not observe any change, it is a real diamond.

Diamonds were formed under intense heat and so are unaffected by heat. On the other hand, other materials will shatter due to the rapid expansion and contraction of the material. 

💡 Caution: Testing a fake diamond with heat can damage the stone. If you don’t want to lose your jewelry, we’d recommend sitting this one out. 

UV Light Test

Diamonds have a blue glow under UV light. This glow is known as fluorescence and it occurs when the diamond contains a trace element like boron or nitrogen that reacts under UV light. However, not all diamonds react this way, so this is not a conclusive test. Other diamond look-alikes like moissanite will give off yellow, gray, or green light.

Sparkle Test

You can run a quick test with your smartphone and suspected diamond stone. The only other thing you need is a pair of observant eyes. Point your smartphone’s torchlight on the diamond, and you’ll see it sparkle brightly. Diamond sparkles are intense and white, not rainbow-colored.

Setting and Mount Inspection

Diamonds are expensive, so they are usually never mounted on cheap metal. If your diamond is mounted on a ring, check that the material is gold or platinum.

To do this, check for the markings engraved inside the ring, such as 14K, 18K, which indicate the quality of gold used. For platinum rings, you’ll see the engravings platinum, plat, or PT. If you see markings such as 585 or 950, it may indicate the quality of gold or platinum. 

If your gemstone is mounted on metals like copper or aluminum, it’s likely fake.

Dot Test 

This test involves white paper, a pen, and your loose diamond. Place your paper on a flat surface, make a small dot with your pen and then place the flat side of your diamond on the dot. Look through the pointed part of your diamond. If you can see the dot through it, it’s not a real diamond, but your diamond is likely real if you can’t.

Diamonds have refractive qualities, so light does not travel in a straight line but bounces in different directions. 

Read Through Test 

This is another test based on the refractive property of diamonds. Use a newspaper, and make sure to wipe your stone clean. Place it on a line of words and see if you can read through it. If you can, your stone is not a real diamond, but if you can’t, then it is a diamond.

💡Take Note: This test works only for loose diamonds.

Inspection With a Loupe 

A loupe is like a magnifying glass but for observing the details of precious stones. It’s another reliable method for those wondering how to tell if diamonds are real.

Using a loupe, look out for inclusions – imperfections found in naturally mined diamonds. There are different types of inclusions and they may look like flecks, a feather, a group of pinpoints, or a crystal, amongst others.

If your diamond has no flaw, it might still be real. Lab-created diamonds usually have no flaw, or they might be hard to find if you’re not an expert. The best bet is to let an expert inspect your gemstone.

Diamond Scale

You need a gem/diamond scale and a caliper for this test – both of which jewelers have. It is best suited for loose stones. Most fake diamonds weigh more than real diamonds of the same size and shape. For instance, cubic zirconia is about 1.7 times denser than diamond. White sapphires are also heavier than diamonds of the same size. However, moissanite weighs less than diamonds.

The Diamond Tester 

Gemologists, who deal with natural and artificial gemstones, use a diamond tester.  This diamond tester is usually called a thermal conductivity probe. The tester sends heat to the stone and then measures how fast the stone conducts the heat. Diamonds disperse heat quickly.

This should be an additional test because moissanite can also disperse heat like diamonds.

Electricity Test

An electricity conductivity tester will differentiate real diamonds and moissanite. Moissanite will conduct a little electricity while diamonds will not.

There are combination testers which are tools that test for both thermal and electrical conductivity.

Frequently Asked Questions

Besides knowing how to tell if a diamond is real, there are other questions you may have, and we’ve answered them in this section.

Does a real diamond sparkle rainbow?

A real diamond does not sparkle the colors of the rainbow, and that’s one of the differences between diamond and moissanite. Diamonds instead sparkle white inside the stone.

Is there an app to test diamonds?

Some apps claim to test for diamonds. Mostly, these apps provide information about diamonds, such as color, cut, and clarity. 

What does a real diamond look like in sunlight? 

Diamond in direct sunlight usually creates a few bright flashes, and the stone itself may look darker.

How much is a genuine diamond worth?

Diamonds are expensive. The rarer they are, the more expensive they get. They are usually worth several thousands of dollars.

How can you tell if a diamond is real or cubic zirconia?

In normal light, cubic zirconia will reflect orange-tinted light, will weigh more than a diamond of the same size, have no inclusions when you view it using a loupe. You can also read our full guide to distinguishing between cubic zirconia and diamond.

Diamonds Are Everyone’s Best Friend

We know the saying is that diamonds are a girl’s best friend but have you met anyone who hates them? No? Us too. 

Diamonds are expensive and a huge investment, so knowing how to tell if diamonds are real is essential. To test your diamond, it is best to take it to a jeweler, as many home tests are not conclusive. When you purchase a diamond, ask for a certificate or grading report to ensure you have the real thing.

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