How To Tell If A Diamond Is Real Or Fake - Complete Guide

How To Tell If A Diamond Is Real Or Fake - Complete Guide

Diamonds are often important parts of many people's prized possessions. We put quite a bit of worth into these stones, whether they're passed down from family members or bought new to celebrate a momentous occasion. But how do you know your diamond is real? There are a handful of at-home methods you can use to test your diamond before you have it professionally inspected by a jeweler.

At-Home Tests vs. Jeweler Inspections

Image via Flickr by Glass and Mirror used under CC By 2.0

Conducting at-home tests can be useful if you're trying to quickly find out whether a gem or piece of jewelry already in your possession is or holds a real diamond. However, we should tell you that these tests are simply clues to point you in the right direction. The only sure-fire way to find out if your diamond is real is by taking it to a professional. So, if it's important that you know exactly what you have in your possession, we suggest skipping the at-home tests.

One of the reasons for this is that modern technology has introduced gems that are difficult for the untrained eye to identify. The usual diamond-substitute suspects — cubic zirconium, laboratory-made diamonds, clear sapphires, moissanite, and others — can be cut and produced to share many of the same qualities as real mined diamonds.

But if your stone fails enough of these at-home tests, you may not have to worry about taking it to a professional. Here are a few methods you can use to identify whether your diamond is real.

Six Methods for Testing Diamonds at Home

If you want to test the authenticity of your diamond at home, there are more than a few methods you can use to do so. For most of these tests, it is better and more conclusive if your diamond is loose. However, you can try some of these while the gem is in its setting.

Black Light

Hold your diamond under a black light and study its color and glow. Most diamonds glow blue under a black light. That being said, not all diamonds glow blue. Some don't glow at all. But, if yours does glow blue, it's likely a real diamond. If your gem glows a different color, such as yellow, green, or gray, there's a chance that it could be a fake.


Take your diamond and breathe on it as though you were about to clean a glasses lens. If the fog from your breath stays on the gem for a few seconds, there's a chance that it's not a diamond. Diamonds are great conductors of heat and don't stay foggy for long. However, keep in mind that this test is not fail-proof — factors such as humidity and gem size may affect your results.


If you want to see if your diamond is actually a weaker stone, such as cubic zirconium, you can heat your diamond with a lighter and put it in a cold glass of water. A weaker stone may crack or shatter due to the drastic change in temperature. This method won't work every time, but you'll know it worked if the gem is damaged afterward.

Magnifying Glass or Loupe

You can use a magnifying glass or a jeweler's loupe to take a closer look at your diamond. What you're looking for are imperfections within the gem. If you find them, that's a good sign — natural diamonds may have flecks of minerals, color changes, and imperfections in general. If you don't find any imperfections, you either have a fake gem, a lab-grown diamond, or a rare flawless natural diamond.

Ring Check

If your diamond is mounted on a ring, you can study the ring for clues. Real diamonds are most often set in quality rings made of gold or platinum. On the inside of the ring, you might find etchings that tell you the quality of the metal used. You especially want to keep an eye out for the initials "C.Z." This marking tells you the stone is cubic zirconium. Keep in mind that stones may change rings and that this isn't a conclusive way to determine that you have a fake diamond.


You can also use water to test your diamond. Simply drop your stone into a glass of water. Real diamonds head straight to the bottom of the glass. If they falter around the middle of the glass or even float, then you likely don't have a diamond.

Don't Just Look for Fake Diamonds

If you're the owner of a fraudulent diamond, it's more likely that it's still a diamond, but not of the quality that you believe it to be. What you'll also be looking for as you inspect your diamond or have it professionally checked is whether or not it's actually a lower-quality diamond made to look like one that's of a higher quality.

This is why it's crucial to inspect a diamond out of its setting if it's at all possible. Sometimes, the setting is masking some sort of flaw in the diamond. In other cases, a diamond's fracture will be filled in, or the gem will be drilled with a laser to make it appear as though it's a higher quality.

Why You Should Have a Trusted Jeweler Take a Look

The absolute best way to tell if a diamond is the real thing or not is by taking it to a professional to have it inspected. Though you can conduct tests like these at home, it's easy to get a false positive or negative with them. A good jeweler will have the necessary tool to let you know conclusively if your diamond is real and what its level of quality is.

The trick is finding a jeweler you can trust — one with the experience and expertise needed to give you quality service and professional work. That's where Martin Busch Jewelers comes in.

Why You Should Choose Martin Busch

Martin Busch Jewelers is the oldest continually operating jewelry store in our neighborhood in Manhattan's Financial District. Our dedication to providing quality services has awarded us with many loyal and long-term customers, some of whom we've been helping for over 30 years. If you're looking for a trusted jeweler in New York City, Martin Busch Jewelers is here to give you the professional service and dedication you're looking for.