Is That Diamond for Real? Start Here to Find Out


One of the most common questions gemologists are asked is how to determine if a given diamond is real or if it’s just a fake stone. Whether you receive a diamond necklace for Christmas, inherit gems or find a possibly good deal at a garage sale, here are some do-it-yourself home tests to help you determine a fake diamond from a real one… or at least whether it warrants a lookover from a professional gemologist.

Use a Loupe to Look at the Diamond

A loupe is a specialized magnifying glass you can obtain from most jewelry stores. It provides for a detailed look at your diamond and the setting. When looking at a real diamond, you should see some imperfections in the carbon. But a fake diamond will have an absolutely faultless carbon. The challenge here though, is that certain diamonds prepared in the lab can also look faultless through the loupe. (Yes, some diamonds created in a lab are considered real) So, be very careufl about discarding perfect stones. If in doubt, bring the diamond to a gemologist for a thorough analysis.

The loupe also enables you to observe the diamond edges. A real diamond has sharp edges, but a fake one almost always has rounded edges. Don’t forget to look at the mountings and etchings, as well as the metal used. A real diamond would most likely be mounted on premium metal such as platinum or gold. If it is mounted on a gold plated or silver plated metal, then you can bet it’s probably fake… why would anyone mount such an expensive gem on a cheap metal?

Breathe On It

Breath hot air on a given diamond, the same way you would to finger-draw on a fogged up car window or bathroom mirror. The fog on a real diamond should dissipate quickly since they’re excellent heat conductors. On a fake stone though, it will keep that foggy look for a few seconds or more.

See How It Sparkles in Light

Diamonds reflect light uniquely. Real diamonds sparkle gray and white (have brilliance) toward the center and reflects rainbow colors onto other surfaces. A fake diamond has rainbow colors visible inside it. Diamonds don’t sparkle like a rainbow—they do sparkle but it’s more of a gray color. If you see anything like rainbow colors inside the stone it’s probably not a real diamond.

Rub Sandpaper against a Given Diamond

Real diamonds are one of the world’s hardest materials, so rubbing it with a sandpaper won’t scratch it though the sandpaper has a rough surface. But something like cubic zirconium will scratch up.

Look at its Refractivity

Real diamonds sparkle because of the way they refract and bend light. Although fake diamond brilliance like quartz, cubic zirconium etc. may resemble that of a real diamond, they have a much lower refractive index. Placing a real diamond onto or just above a newspaper, the light will scatter inside the real diamond and prevent a true black reflection. But with a fake diamond, the black shines through almost like a magnifying glass. You may even be able to read the print depending on the size of the fake diamond.

Note: As Live Science explains, even a real diamond may fail the newspaper test if it’s cut too shallow.

Always Test with a Gemologist

The last ultimate test is to take the given diamond to a gemologist. The tests described above are just home tests and are simply ways to help determine if it should be given a closer look by a professional.

Veronica Davis