How to Tell if a Diamond is Real or Fake

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How to Tell if a Diamond is Real or Fake

Round Brilliant Cut Diamond

This page contains references to diamonds or engagement rings from different companies. Sometimes I do receive a commission when you click on links and buy the products.

This guide is designed for those of you who have a piece of jewelry you want to be sure contains real diamonds. You
can rest assured that when you purchase a new piece of diamond jewelry, as long as you buy from a reputable dealer you are getting the real deal. This can be confirmed with the GIA or AGS certificate you’ll be able to see prior to the point of sale.

Many people have jewelry at home that they don’t know the full heritage of. Perhaps it was a gift, or an heirloom. Your attachment and perception of the piece is likely to be tied up in emotion more than fact, however, it can be useful and worthwhile to be able to tell if a diamond is real or fake. Unfortunately, for many inexperienced onlookers looking with the naked eye, you won’t always be able to tell at first glance whether the stone you’re looking at is an authentic diamond or perhaps cubic zirconia – the main imposter of the real deal.

I’m going to go through some hints and tricks that you can use to determine whether a diamond is real or fake. However, not only do I recommend using more than one approach, I also recommend only using them as a guide. You should also get an expert opinion to be sure.

Home-Based Tests for Real v Fake Diamonds

The Breath Test:

Suitable for any gemstone, even within a setting, is the breath test. Simply hold the piece close to your mouth and breathe out a harsh breath directly at the stone so that it fogs up. Quickly look at the jewel. How quickly did the fog go? Quickly – it’s likely to be a diamond because they are great heat conductors. If it lingers however, it’s more likely to be fake.

The Water Test:

Probably the easiest way of eliminating the most obvious imposters is testing whether your stone sinks or floats. Sinks – it’s more likely to be a diamond because they have a high density. Float – it’s a fake. However, here you have a problem because unless you have been able to remove the gemstone from the setting, the setting itself will of course cause the piece to sink.

The Heat Test:

Warning, don’t try this if you want to keep the gem (real or fake) in its entirety. The real deal will survive this test, but a fake won’t. Fill a glass with cold water. Then, using tweezers or pliers hold the stone within the flame of a lighter for around 45 seconds. Then plunge it in to the cold water.

A diamond is intensely strong and will remain unchanged. However, other materials, such as cubic zirconia or glass, will shatter, crack or break because of the stress caused by the temperature change.

The Setting Test:

If your diamond is set within a piece of jewelry, this can offer some clues if you put on your detective hat. Diamonds are, and always have been, highly valuable. As such you simply don’t find them in low quality settings.

To be sure, look inside the ring, or on the back of a pendant, and take a look at any markings. If there aren’t any, that’s your first clue that this is unlikely a diamond. If there are markings look with a magnifying glass to see what they are. You’ll see combinations of letters and numbers which pertain to gold, white gold, and platinum – all of which you’d expect with a diamond. However, if you see ‘CZ’ then it’s cubic zirconia and not the real deal.

The UV Test:

If you can get hold of a UV light then this is a good option because you’re starting to look beyond the naked eye. When exposed to UV light many true diamonds will emit a blue-hued light. However, just because you don’t get the blue glow don’t despair, this particular test is far from definitive.

The Refractivity Tests:

One of the primary reasons we love diamonds so much is because of their sparkle – that bright dazzle that you get as it moves in the light. It even has a technical term: brilliance. This dazzle and dance of light is due to refractivity between the pavilions and the table of the diamond. Of course, different quality and caliber diamonds themselves have different amounts of refractivity, and thus brilliance, so testing this at home isn’t an exact science. However, generally speaking, the greater the refractivity, the higher the chance you’re looking at an authentic diamond. There are two ways you can do this at home:

The Spot Test:

Simply get a piece of white paper and draw a small spot on it in pen. Just a millimeter in size will do. Then lay your gemstone on top of the spot, table (flat) side down. Make sure the lighting around and above the diamond is bright. Now look through the diamond. Can you see the spot? If so, it is unlikely it is a real diamond.

The Reading Test:

Slightly more accurate than the spot test is to take a page of print (such as newspaper or a magazine). Apply the same principle as the spot test, but this time see if you can make out the printed letters, even if blurry. With a real diamond you simply won’t be able to make out the letters at all because the light is refracted all over the place.

Don’t attempt either refractivity test if the diamond is within a setting.

The Sparkle Test

If you think of refractivity as the dance and dazzle of the light, then reflectivity is the amount of light which bounces back off the stone – the sparkle. Again, this is subjective and a scale. A diamond will reflect both the bright white light and the colored light to create a mesmerizing sparkle.

Simply hold the diamond under a light and gently move it around. Do you see a mixture of white and colored light reflecting off the surface of the diamond? If so, it is more likely to be real than fake.

Expert Tests for Real v Fake Diamonds

Understandably, whilst the above home-based tests will give you some indication as to whether your diamond is real or fake, none are failsafe. You should consult the experts. A professional gemologist, most notably those with Graduate Gemologist status, will be able to draw on their skill, knowledge, tools and techniques to give you a definitive answer.

The Loupe Test:

Much like a doctor carries a stethoscope, a diamond expert will always carry a loupe. This is a technical magnifying glass enabling them to look beyond that which the naked eye can see. They will quickly be able to spot a fake as well as nature of the inclusions if your gemstone is a diamond.

The Thermal Conductivity Test:

Think back to the home-based heat test where I suggested holding the gemstone in a lighter flame. Diamond experts can do this test more scientifically and accurately using a thermal conductivity meter. As with the home-based test the aim is to test how well the stone copes with a change of temperature. Diamonds conduct heat extremely well. However, even an expert knows that some fake diamonds (such as moissanite) can equally disperse heat.

The High Profile Weight Test:

One of the scientific methods for testing whether a diamond is real is looking at its weight. However, even with the largest gemstones, the differences in weight that we are looking for is far too small to detect using home equipment. Diamonds will weigh less than an equivalent-sized stone such as cubic zirconia. However, only a diamond expert will have carat scales capable of measurements this small.

The Electricity Conductivity Test:

Much like heat, diamonds also conduct electricity more efficiently than other stones. This means that an expert diamond professional can attempt to conduct electricity through the stone. If the stone conducts electricity, it is most likely to be a genuine diamond. Even the artificially created moissanite, which proves tricky on the thermal test, will be detected on the electricity conductivity test.

A Word on Moissanite

Moissanite is a tricky culprit when it comes to determining real vs. fake diamonds. Whereas cubic zirconia has many giveaway signs, the synthetically created moissanite has less. Home-based tests should give you a pretty good indication if you’re holding cubic zirconia, but they will prove considerably less reliable for testing if it’s moissanite. You’ll need the skills and tools of an expert here.

The Myths of Real v Fake Diamonds

It’s not unusual to still hear that you can tell if a diamond is real or not by whether it is capable of scratching glass or a mirror. Whilst of course there is truth behind the phrase ‘tough as diamonds’ this scratch test has some obvious pitfalls. Firstly, unless the diamond isn’t in a setting you’re going to have a problem logistically trying to do this. Secondly, the fake diamonds which exist now – such as moissanite and cubic zirconia – serve as fake diamonds precisely because they share some of the characteristics of a real diamond. They could also scratch your glass or mirror. It is a wholly unreliable method.

Types of Fake Diamonds

There are many imposters! Some are easier to spot than others. Let’s take a quick look at the different types:

  • Cubic Zirconia: This is the most common culprit masquerading as a diamond. The good news is that it is amongst the easiest to spot. With a little understanding most people can see clearly that they don’t refract and reflect light to the same degree as a diamond. They are also heavier.
  • Synthetic Diamonds: Technology has advanced for creating synthetic diamonds in a lab. These diamonds can appear, even to experts, very similar to authentic diamonds formed over millions of years. The only way to spot these is to enlist the help of an expert who can look carefully at the internal structure and perform a conductivity test.
  • Moissanite: As hinted at already, moissanite really is the toughest imposter to spot in the line-up. This particular synthetic diamond has many similarities to the real deal. However, an electrical conductivity test will still show moissanite up as the imposter it is.
  • White Sapphire: We’re accustomed to thinking of sapphires generally as blue, however, they are on a scale from blue through to white. Whilst sapphires of any hue are wonderful stones in their own right, a white one can sometimes be passed off as a diamond. However, there are notable differences between a diamond and a white sapphire, most specifically the refraction and reflection. An expert will be able to help.
  • White Topaz: White topaz is another stone that mimics some of the looks of a diamond at first glance. Yet, when inspected more closely, there are numerous ways in which white topaz is distinctly different. Typically, topaz is considerably softer than diamond and the surface can easily become scratched. Even if these scratches aren’t visible to the naked eye, they will be visible using a loupe.

How to Be Sure a Diamond is Real

The only definitive way to be certain whether your suspected diamond is real or fake is to arrange for it to be tested by an expert diamond professional. The home-based tests above can only give you a general indication, or help to raise your suspicions.

Authentic diamond retailers, such as Whiteflash, James Allen and Blue Nile can point you in the right direction. Additionally, they can also assist if you’re considering getting your loose diamond set in jewelry, or making a diamond purchase which is backed up with authenticity certifications. Owing to the number of rogue traders and fake diamond options out there, it always pays to rely on professional diamond experts who have both technical knowledge and the tools needed to spot a real diamond from a fake.

Richard Jenkins
Richard Jenkins
Richard Jenkins, known as Your Diamond Guru, is a diamond enthusiast who became an expert after searching for an engagement ring for his fiancée. Frustrated by the lack of guidance, he studied diamonds and became the go-to person for advice on buying the best diamonds. Richard launched Your Diamond Guru to provide unbiased reviews and resources to help others make informed purchasing decisions. He emphasizes the importance of considering factors beyond size, such as cut, color, clarity, carat, certification, and light performance.

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