How to Tell if Your Diamond Is Real or Fake With 5 Home Tests

Want to know how to tell if a diamond is real? Use these at-home tests to find out if a diamond is real without having to see a professional jeweler.
by Angela Guzman

Buying a diamond is an emotional purchase, so of course you'll want to know whether or not a diamond is real before you sign on the dotted line. But how can you tell if a diamond is real? Whether you're in the market to purchase a diamond ring or you want to inspect your own jewels, it's normal to understandable that you’d want to know the authenticity of your stone. Diamonds have several "fake" counterparts that can easily be mistaken for real diamonds—natural gems with a strong resemblance to diamonds are colorless sapphire, colorless topaz and colorless zircon. There are also gems created in a lab, like YAG (yttrium aluminum garnet), GGG (gadolinium gallium garnet), CZ (synthetic cubic zirconia) and synthetic moissanite that look like real diamonds to the average person. This probably leaves you wondering how to tell if a diamond is real if there are so many look-alikes. 

Experts advise that you do your homework. “The biggest misconception is there's just one type of ‘fake.’ There are several diamond substitutes and stimulants on the market. Some of these substitutions have value in their own right—others are completely worthless,” says Shannon Delany, director of communications for James Allen. A real diamond has some qualities that can’t be faked.

Pro tip: It’s also important to know if the diamond is certified within one of the three top grades – GIA, AGS, and IGI. When in doubt, you can use tools like Diamond Display Technology provided by James Allen that reviews and evaluates inclusions. 

Of course, you want your stone to stand the test of time. So if you’re questioning whether or not a diamond is real, we highly recommended you seek out the advice of a reputable jeweler. However, if you’re in a pinch, we have five simple tests  you can use at home to tell if a diamond is real or fake.

Real vs. Fake Diamond: How to Know if a Diamond Is Real Using 5 At-Home Tests

Before we dive into the home tutorials, it’s important to know the difference between mounted and loose diamonds. how to tell if a diamond is real will vary, depending on whether the diamond is loose or set in a mounting.

It’s easiest to test a loose diamond, or one that hasn’t been mounted in a setting, for both authenticity and determining if there are any flaws. Often, mounted diamonds’ mountings can hide potential flaws, cracks or chips. Mountings also usually reflect light into the diamond, which makes it difficult for anyone but a reputable jeweler to assess the stone’s clarity or color. If you’re purchasing a mounted diamond, you may want to ask the jeweler to remove the stone so you can have it thoroughly inspected while it’s loose.  

“Occasionally, we do encounter stones that are not real diamonds. What we see more often than not are actually real diamonds of poor quality or enhancement,” says Judd Rottenberg, principal at Long Jewelers, graduate gemologist at GIA and certificated gemologist at AGS. “For example, laser drilling and fracture fill are two ways to alter a stone to [make it] look better than it actually is.”

Rottenberg says another big misconception is that real and fake diamonds look the same. “At first, a diamond and a cubic zirconia may look similar, but in a short period of time, a cubic zirconia stone will lose its brilliance and look damaged,” Rottenberg says. “It’s not as hard as a diamond and won’t wear as well.” So, if you’re wondering how to know if a diamond is real, know that the while the test of time will tell you, there are other ways to test your stone, too.  

Now it's time to test your diamond. While each of these tests can be done on a loose or mounted diamond, you’ll find it’s likely easier to distinguish between real and fake if you have a loose diamond.

1. How to Tell if a Diamond Is Real With Fog

To tell if your diamond is real, place the stone in front of your mouth and, like a mirror, fog it up with your breath. If the stone stays fogged for a few seconds, then it's probably a fake. A real diamond won't fog up easily since the condensation doesn't stick to the surface. 

2. How to Tell if a Diamond Is Real With Water

This one's easy: Get a glass and fill it with water (it doesn't matter what type of water you use). Drop the diamond into the glass of water. Due to the high density of diamond, when dropped into water a real diamond will sink. If the diamond floats to the top or middle of the glass, it's fake. It's simple physics. 

3. How to Tell if a Diamond Is Real With a Magnifying Glass

To determine if your diamond is real, hold a magnifying glass up and look at the diamond through the glass. Look for imperfections within the stone. If you're unable to find any, then the diamond is most likely fake. the majority of real diamonds have imperfections referred to as inclusions. There are flawless diamonds out there, but they’re either lab created or pretty pricey. 

4. How to Tell if a Diamond Is Real With a Black Light

You'll need a black light for this one, obviously. Once you have it, turn off the lights and hold the diamond in front of the black light. Most diamonds will reveal blue florescence under a black light; therefore, you'll see a medium to strong color of blue, which means the diamond is real. If you don't see the blue color and instead see a slight green, yellow or gray fluorescence then this usually indicates the gem is not a real diamond. But remember: This is not a conclusive test and not all real diamonds will reveal a blue fluorescence. 

5. How to Tell if a Diamond Is Real With a Loupe

A loupe is a small magnification device that's used by jewelers to see small details up close. The difference between a loupe and a magnifying glass is simply that a loupe doesn't have an attached handle and its lens frame is slightly more conical. Most jewelers use loupes when inspecting diamonds for class and clarity. If you don't have one (weird!), Amazon has a large selection of loupes to choose from for a reasonable price.

Once you have one, look through the loupe, look for inclusions. Mined diamonds usually have tiny, natural imperfections which indicate the diamond is real. Next, check to see if there are small flecks of minerals or slight color changes. If there are signs of slight color changes and flecks, then the diamond is more than likely real. (Keep in mind that some diamonds are flawless. If there are no flaws or imperfections, this doesn't necessarily mean that you're dealing with a fake, but it does mean you’re dealing with a rare perfect diamond). While most real diamonds often have imperfections, don't rely on this method as your final determination. Lab-created diamonds normally don't have any imperfections since these gems are produced in controlled environments. 

So how can you tell if a diamond is real? Try these five at-home tests and see how your stone responds. They’re not all fool-proof, but they’ll give you a good idea about whether you should be suspicious of your diamond or not. Most importantly, if you doubt that what you have is a real diamond, particularly if it did not pass one or more of the at-home tests, it never hurts to take it to a professional jeweler for evaluation. They can give you more information about your stone and the peace of mind that your diamond will last a lifetime. (Plus, it doesn’t hurt that they’re actual experts in how to tell if a diamond is real.)

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