How To Tell If A Diamond Is Real – Your Ultimate Guide [2021]

how to tell if a diamond is real

Not everyone is armed with knowledge about a diamond’s structure, components, and composition, so oftentimes when we look at a gem, we can’t tell whether it’s a real diamond or not.

Not knowing a thing or two about diamonds can lead you to believe that a stone you are looking at is a diamond when it is an entirely different stone.

For example, that bag of gems your grandmother left you as an heirloom may not solely be all diamonds, but white stones resembling a diamond.

In this guide, you’ll learn:

  • How to Tell if Diamonds are Real or Fake Using Different Tests
  • Recognizing Diamonds from Other Stones

How To Tell If A Diamond Is Real Or Fake

At Home

At-home practices for assessing real vs. fake diamonds are not entirely reliable, but they can be unexpectedly accurate. These tests can be done with a few items you can find in your garage or cupboard.

Water Testwater test

This simple test will show you whether your diamond is real or fake. What you need is an average-sized drinking glass. Fill it ¾ of the way with clean water. Then, carefully drop the stone into the glass.

You’ll know it is real if it sinks. If it swims underneath or at the surface of the water, you have a questionable stone in your possession. The logic behind this test is due to the diamond’s high density causing it to be submerged.

Take note, however, that this test isn’t foolproof. Cubic zirconia or glass that have been well cut and are heavy could pass this test.

Fog Test

Remember how you fog up your eyeglasses to clear it up? This step is as easy as that. This quick and easy way to tell whether your diamond is fake is real needs you to hold the stone in front of your mouth and fog it up with your breath – just like you would on your eyeglasses.

If the fog clears up in a second or two, yours is a genuine stone. But, if it stays fogged for more than two seconds, you are holding a fake gem.

Diamonds disperse heat instantaneously, making it impossible to fog up. Condensation also doesn’t stick to the surface.

Be sure to clean your diamond before performing this test. There shouldn’t be any traces of oil present, or the test may give inconclusive results.

Setting and Mount Check

Diamonds come with a hefty price tag, so it is not surprising that it also comes set in high-quality jewelry. Jewelers won’t mount a diamond in a cheap metal. They’d most of the time be in materials like white gold, platinum, yellow gold and in a pave, side-stone, or halo setting.

Check if the ring is indeed what was described. It should have markings in the center that will make you identify its authenticity. For instance, you may see notes like 10K, 14K, or 18K as an indicator of the type of gold used. PT, or Plat, refers to platinum.

Don’t be confused if you show numbers such as 585, 770, 900, and 950. They are markings that indicate platinum or gold, too. CZ stamp refers to cubic zirconia.

Heat Test

lighter test

Another technique to determine if your diamond is real or fake is by using heat.

Take a lighter and light the stone for about 30 to 40 seconds before dropping it in a bowl of cold water. Fake diamonds will shatter into pieces but not real ones. It won’t even react to both temperatures. Diamonds are solid and exceptionally strong that it stays unresponsive to extreme heat or cold.

This method tests the quality and strength of the stone. Heat causes expansion and contraction; therefore, weak materials like cubic zirconium will crack and break into pieces. For instance, your Pyrex dish – pulling it out from the oven and immediately washing it may shatter the container because of shock in temperature.

Black Light Test

uv light test

If you have a blacklight or UV lamp at home, you can use it to test whether you have a natural diamond. Simply turn off the lights and hold the gem in front of the black light. The majority of diamonds will reflect blue fluorescence under black light.

You will see medium to solid shades of blue that tell you your diamond is real. If it shows slight green, yellow, or gray fluorescence instead of anything bluish, the gem you are testing is fake.

But, this test may give uncertain results since not all diamonds reveal blue fluorescence.

Newspaper Test

Newspaper Test

The newspaper test, or the “read through” effect, will test your diamond’s refractivity.

On a newspaper page, place the stone flat-side down in an area with lots of print. Ensure that the lighting is bright and that nothing obstructs the light or casts a shadow on the diamond.

If you can read the letters on the page where the diamond is placed – even if the inscription is blurred, the diamond you are testing is fake. Real diamonds have their facets that refract the light in different directions instead of a straight line, making it hard to see through it.

Here’s a video showing how the newspaper test is done.

Dot Test

Dot Test

If you have no access to a newspaper, the dot test is an excellent alternative.

You will need a white piece of paper lying flat on a surface. Draw a small dot with a pen or marker. The next step is to lay the stone directly onto the dot you drew. Examine if you can see a circular reflection inside the gemstone by looking through the pointed end of the diamond.

If you can see one, the diamond you are looking at is fake. If you can’t, it is real. The logic behind it is that a real diamond possesses strong refractive qualities that make light bounce in different directions instead of a straight line.

Sparkle Test

Sparkle Test

This test won’t require any equipment except for your eyes.

Under a regular lamp, hold the diamond and what how the light reflects off of it. Does it shimmer with white light bouncing off the diamond? Are there colorful light reflections?

A real diamond returns white light exceptionally well, delivering excellent sparkle. It also reflects colored light, or fire, brilliantly.

Placing a real diamond side-by-side with cubic zirconia will show you a big difference in white and colored sparkle both gems give off.

With Expert’s Help

While the methods we mentioned can help spot the real diamond from the not, nothing beats a professional’s expertise. The knowledge they have from a degree in Gemology will help you identify whether your diamond is fake or real reliably.

Using the Loupe

The most common device you will see from a jeweler is a loupe. This device lets them see small details up close. Loupe is a magnifying glass that doesn’t have an attached handle and with a lens frame that is more conical.

With a loupe, a jeweler can see the diamond for its blemishes and imperfections. Fake diamonds are usually made to look perfect. So perfect that they miss inclusions that are typically found in diamonds.

Using the Thermal Conductivity Probe

More commonly known as the diamond tester, the thermal conductivity probe tells a gemstone’s thermal conductivity.

Diamond is an efficient heat conductor. So efficient that it disperses heat rapidly after being warmed. In this method, if the gemstone’s heat dissipates speed at a slower rate, it suggests that the diamond is not real.

Keep in mind that synthetic moissanite stones possess similar heat scattering nature of diamonds, which can result in an uncertain outcome with moissanite.

Diamond testers can be purchased even if you aren’t a jeweler. You can check out Amazon for this device. Be sure to read the comments first before adding them to your cart.

High Profile Weighing

Not everyone has access to a diamond scale. It is one of the most sophisticated tools jewelers to weigh diamonds and other jewelry pieces and determine whether the diamond is real or fake.

Smart Weigh GEM20 High Precision Digital Milligram Jewelry Scale

These scales are finely tuned to measure even the tiniest difference in weight. A real diamond’s weight will always be lower than fake stones – and unique scales such as diamond scale for weighing carats will be able to tell these detailed differences.

To do this test, compare the diamond in question to a fake diamond approximately equal in shape and size.

Using Electricity Conductivity

Diamonds conduct electricity a lot better than other stones, including the difficult to differentiate – synthetic moissanite. Because of this, doing an electrical conductivity test on the stone in question can tell whether your diamond is real or fake.

Recognizing Diamond From Other Stones

The rising popularity of other gemstones may confuse you into thinking you have a diamond when you have a different kind of stone that happens to appear similar to a diamond. Here’s differentiating diamonds from other gemstones.

Diamond vs. Synthetic Diamonds

Synthetic diamonds are slowly becoming prevalent in the market. It is crucial to know how to differentiate a lab-created diamond from a real diamond. It can be a little tricky since both have the same chemical and molecular components.

It is recommended to seek assistance from an expert because of their intricate internal qualities. An expert will run a conductivity test and look at the stone under extreme magnification. While the difference between the two is unclear to the naked eye, it is still essential to know for resale and insurance purposes.

Diamond vs. Cubic Zirconia

One of the easiest to spot as a fake diamond in an authenticity test is cubic zirconia. It is pretty easy to find out with a simple sparkle test based on the amount of sparkle and fire it gives off.

Moreover, cubic zirconias return orange-tinted light, and they weigh more than a real diamond. They are generally perfect with no blemishes nor inclusions. Natural diamonds have inclusions that are either obvious to the naked eye or under a diamond expert’s loupe.

Diamond vs. White Sapphire

Although sapphires are commonly available in blue, they come in a wide range of colors, including white. These white sapphires look bright to the naked eye and can easily pass as a diamond. The difference is – sapphires don’t bring the same sparkle and contrast of dark and light areas like that of a diamond.

If the gem you have seems hazier in coloring and does not have evident light and dark parts, it is highly likely to be a white sapphire.

Diamond vs. Moissanite

Moissanite has to be the best diamond pretender. The distinction between them is pretty tricky to tell for the naked eye. So complex that it may require the expertise of a gemologist.

The most effective way to tell them apart is through an electricity conductivity test. This test is different from a thermal conductivity test – which is not a valid method for recognizing moissanite as they have just about the same thermal conductivity.

Diamond vs. White Topaz

Another gem that can easily pass as a diamond is a white topaz. At first glance, its brilliance will have you mistaken it as a diamond. But, it has many characteristics that separate it from a diamond.

Its exterior is relatively softer than a diamond and can be easily scratched by other materials. You may also closely look through a loupe to see if there are other scratches on its surface. Diamonds, with their solid and durable composition, will never have any scratches.


Most tests we’ve included in this guide can help determine whether your diamond is natural or not.

However, the complexity of the synthetic gemstones available in the market today may leave you clueless if not confused. The best way to tell if the diamond you have is natural is to visit experts. These people studied these stones and are trained in knowing which diamond is real.

If you have been following our posts regarding diamonds, you won’t have a problem figuring it out. You are armed with an understanding that the best assurance your diamond is what it says it is, is the legitimate GIA or AGS certificate it comes with.

FAQs (Frequently Asked Questions)

Q: Is testing your diamond’s authenticity with sandpaper effective?

A: The internet is saturated with countless ways to spot a fake diamond, but not all are effective. Some may even destroy the gem in question. Imagine if it turns out to be a genuine gemstone but got damaged because of what you did to it.

Scratching with sandpaper is one destructive test that should never be done. Sandpaper has grit with a hardness between 7 and 9 on a Mohs scale. Using sandpaper on a material softer than the grit will only harm it. You risk not only rubbing and scratching the metal in which the stone is set but also chafing the gem’s surface and diminishing its worth.

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