10 Ways to Tell If a Diamond Is Real, According to Jewelers

When you're first examining your own diamond or that of a loved one, you may take notice of the 4Cs associated with the jewel: its cut, color, clarity, and carat weight. The first, cut, ultimately dictates how it interacts with light. The gemstone's ability to reflect light back to you accounts for much of the sparkle we commonly associate with diamonds. Once you've looked at the jewel's cut, you may begin to inspect its color, which can range from colorless to light yellow. And while the first two Cs may be easy to notice and determine, the third, clarity, is a bit trickier. This C refers to the number of imperfections, also called inclusions, in your gemstone. Oftentimes, you may need a professional to help you fully understand—and see—the clarity of a stone. Yet the last C is likely one you're aware of: the carat weight of the diamond, which often plays a large role in influencing the sparkler's cost. After considering each of the 4Cs, another thought may cross your mind: how to tell if a diamond is real.

Modern synthetics can easily resemble diamonds, making it difficult for someone who isn't a professional to determine the validity of any jewel simply by looking at it. However, while the best way to know whether a gemstone is real is to have it examined by a trusted jeweler, there are a few at-home tests that can help indicate whether you should be skeptical of your sparkler. Yet before proceeding with any assessment, know that the result depends a lot on what the stone is made of. "Not everything is cubic zirconia (CZ)," says Nicole Wegman, founder and CEO of Ring Concierge. "There are different synthetics and different ways to make a fake diamond. You really should do a variety of these tests before you jump to conclusions that the stone is real. It might pass one test, but then not others."

Curious to see whether or not your diamond is real? Below, the experts break down different methods to assess your jewel.

Can an At-Home Test Determine Whether a Diamond Is Real?

Potentially. While there are many methods for testing whether a diamond is real or not without the help of a professional, these evaluations do have flaws and can't be trusted to be 100 percent accurate. "There are at-home tests you can do to determine if a diamond is real or not," says Ashley Zhang, a fine jewelry designer. "However, we always like to recommend having a diamond professionally tested and certified." For example, the UV test—a common at-home method—calls for you to place the diamond under a UV light. If the gemstone gives off a blue glow, it's thought to be real. However, Zhang points out that not all diamonds have fluorescence, which is what emits that cool color when placed under the light. And as a result, you may be led to believe that a real diamond is actually fake.

How Do Jewelers Determine If a Diamond Is Real?

Compared to the average person, professional jewelers and gemologists have more tools at their disposable to see whether or not a gemstone is real or synthetic. "In the trade, we rely on specialized tools like diamond testers that measure thermal conductivity or moissanite testers to rule out common lookalikes," says Katherine Kim, the founder of KATKIM, a Los Angeles-based fine jewelry brand. "Labs also use advanced techniques like spectroscopy and X-ray analysis."

How to Tell If a Diamond Is Real: 10 Methods to Try

While the best way to determine if a diamond is real is to have it evaluated by a professional, there are some methods that can help indicate whether you may be dealing with a synthetic gemstone. Here, the experts break down different methods you can try at home—and what to keep in mind when testing out each one.

Check Its Brilliance

It's one of the most alluring qualities of a diamond: its sparkle. However, apart from being aesthetically pleasing, this twinkling factor can also help you determine whether or not your stone is real or synthetic. "Focus on the brilliance," Kim says. "A real diamond reflects light uniquely, creating that unmistakeable sparkle." Zhang echoes this sentiment: "Diamonds are highly refractive, so they will sparkle more as they reflect light well."

Look for Inclusions

The inclusions or imperfections that determine your stone's clarity are difficult to spot without the help of professional tools. However, looking for these can be key in determining whether or not your sparkler is real. "The inclusions are also a great indicator that a diamond is real as [they] occur naturally during its formation," Zhang says.

Initiate the Fog Test

"If you want a quick at-home indicator, the fog test is a bit more reliable [compared to other tests]—breathe on the stone, and if it clears quickly, it’s likely real," Kim says. Wegman explains the science behind this method: "If it’s a real diamond, it’s less likely to fog up because the condensation doesn’t stick to a diamond in the same way it’s going to stick to a synthetic," she adds. However, even such a test doesn't top a professional evaluation, Kim notes. If this tactic leads you to believe you may be handling a synthetic gemstone, take it to a jeweler to be further examined.

Scratch Your Stone

While they may appear fragile, in actuality, diamonds are difficult to mess up. Aside from another diamond, nothing can scratch them. To truly test your gemstone, consider taking a knife and gently scratching the top of the stone. "If it scratches, it’s not a diamond; it’s certainly synthetic," says Wegman. "The idea of trying to scratch it probably isn’t going to be the easiest thing to stomach, but a true diamond will not scratch from stainless steel, whereas a CZ would scratch immediately."

Perform a Quick Hot/Cold Test

This test can also be anxiety-inducing. To perform it, start by holding your stone over a flame—and then drop it into a glass of ice water. While a real diamond won't shatter, a synthetic one will, due to the extreme temperatures. "You can put as much heat as you can imagine up to a diamond with no damage," Wegman says. "A fake cannot handle heat like that."

Try the Float Test

If you'd rather not risk potentially damaging your stone, consider the float test. In this assesment, you drop your stone into a cup of water. If it sinks, it’s likely real, but if it floats, it's likely synthetic. However, note that this test isn't always 100 percent accurate. "The water test is also not foolproof because other diamond simulants, such as CZ, may be heavy enough to sink in water as a diamond would," Zhang notes.

Purchase an At-Home Diamond Tester Tool

Apart from heading to your jeweler, the most accurate testing tool you can use is an at-home diamond selector tool. "It’s a pretty small handheld device that you just turn on and touch to the stone," Wegman says. "It will tell you immediately if it’s a diamond." However, before purchasing this evaluator, she suggests looking at online reviews to ensure you're buying a legitimate version.

Examine the Setting and Band Metal

Taking note of the setting and band metal can be just as helpful as examining the diamond in determining whether it's real or not. "High-quality diamonds are almost always set in equally high-quality metals like platinum or 18K gold," Kim says. If your setting isn't made of high-quality gold or platinum, you may be looking at a synthetic stone. Additionally, examine how the stone is set: "Synthetic stones are often set with glue and not prongs," says Grace Lee, the founder of Grace Lee Designs.

Try the Line Test

"The line test is one where you draw a black line on a white sheet of paper," Lee says. "When you place a synthetic stone on it, you can see the line. When you place a diamond on it, you cannot see the line." This is due to the way diamonds refract light, making it impossible to see through them. However, know that some synthetics, such as moissanite, can be highly refractive, allowing them to pass such a test, Zhang cautions.

Head to a Jeweler

If you want to be completely sure as to whether or not your diamond is real, head to a trusted jeweler or gemologist. Such an expert will be the best person to definitively answer this all-important question. "Nothing beats a professional evaluation," Kim says.