The Jewelry Box Blog

How to Tell if a Diamond is Real vs Fake

real diamond inspection

Grandma’s antique “diamond” is big and beautiful—but is it authentic? When buying or selling diamond jewelry, including engagement rings, it’s important to know how to spot a fake diamond. 

Below are some red flags, shopping tips, and DIY tests you can conduct to determine whether it’s a real vs. fake diamond.  

Common Diamond Look-Alikes

The first step in determining a real vs. fake diamond is to arm yourself with some basic knowledge about the gemological characteristics of diamonds, and how they are graded and priced (an assessment the diamond industry calls the 4Cs, for carat, color, clarity, and cut). 

The gemstone supply chain is filled with stones that have a powerful resemblance to authentic diamonds but aren’t the real thing. Known as diamond simulants, they include cubic zirconia (CZ), yttrium aluminum garnet (YAG), and moissanite (very sparkly silicon carbide).  
Lab-created diamonds and natural gemstones including white sapphire, white topaz, and white zircon are also abundant, and some couples even prefer them for engagement rings because they’re lower priced than mined diamonds but still deliver plenty of sparkle. Moissanite engagement rings are popular with both designers and retailers.  
But if you’re shopping for a diamond, the best way to ensure you’re getting the real deal is to shop with a local jeweler, ideally one that friends, or family members have vouched for. Why? Unless you’re a jewelry pro, telling the difference between a real vs fake diamond can be confusing and potentially lead to a financially devastating mistake. 

Now that you know what the “look-alikes” are, it’s time to further protect yourself.

Sketchy Diamond Seller Red Flags

No one wants to spend thousands of dollars on a fake diamond that has been advertised as genuine only to find out that it will neither withstand the test of time nor appreciate in value. Dishonest sellers tend to use the same playbook. Look out for these seller red flags.

diamond grading report


1. There’s no documentation 

High-value diamond purchases, whether new or antique, should be accompanied by a grading report from a reputable gem lab like the Gemological Institute of America (GIA), the American Gem Society (AGS), or the Gem Certification and Assurance Lab (GCAL). A diamond certificate or grading report from one of these firms is the gold standard for verifying gemological properties of a stone and confirming its authenticity. The absence of one, especially for purchases over $5,000, should raise concerns, especially if you know nothing about the seller.

2. Cash only terms

Paying cash is okay if you know the seller is legit. Otherwise, always pay with a credit card so that you have some recourse should you become the victim of fraud. And save the receipt!

3. There’s no return policy

Final sale? Oh, heck no. Walk away. The stakes are too high! 

DIY Diamond Tests to Try 

Whether you’re trying to determine the authenticity of an heirloom stone or vetting a diamond from a seller you’re not sure about, there are few things you can do to verify whether it’s a real vs. fake diamond. 

diamond tester device

1. Use a diamond-tester 

Does that price seem too good to be true? It probably is. You can purchase a diamond-tester, an electronic device that measures thermal conductivity in 30 or so seconds, for about $15 online. Make sure your diamond is clean and follow the instructions carefully.  

2. Rub it 

Get some sandpaper and gently rub the gritty side against the stone. If it’s a real diamond, it will not cause any damage but if it’s one of the fakes, it will scratch.   

3. Read it 

The read-through test is often conducted on loose diamonds (not mounted to a piece of jewelry). Grab a sheet of paper that has plain black text, turn the diamond upside down, and look through it. If you are able to read the words, the stone is fake. 

4. Breathe on it 

Breathe directly on the diamond. If it’s genuine, the diamond won't fog up easily because the condensation shouldn’t stick to the surface. If the fog remains on the stone for several seconds, then it's most likely not genuine.


The best way to avoid becoming a victim of a scam is to purchase quality diamonds and other jewelry from a local and reputable jeweler with a clear return policy. These pros have the knowledge, tools, and equipment to determine the authenticity—and verify quality—of a diamond. Further, the jeweler will take the time to educate you and answer your questions.  
Once you’ve determined the diamond is authentic and you feel good about buying it, protect your investment by getting it insured. Whether it’s a new jewel or an antique diamond piece you have had for some time, obtaining jewelry insurance through Jewelers Mutual is an affordable option and covers loss, damage and disappearances. You can check your rate by clicking the button below.




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About Jewelers Mutual Group

Jewelers Mutual was founded in 1913 by a group of Wisconsin jewelers to meet their unique insurance needs. Later, consumers began putting their trust in Jewelers Mutual to protect their jewelry and the special memories each piece holds. Today, Jewelers Mutual continues to support and move the industry forward by listening to jewelers and consumers and offering products and services to meet their evolving needs. Beyond insurance, Jewelers Mutual’s powerful suite of innovative solutions and digital technology offerings help jewelers strengthen and grow their businesses, mitigate risk, and bring them closer to their customers. The Group insurers’ strong financial position is reflected in their 37 consecutive “A+ Superior” ratings from AM Best Company, as of November 2023. Policyholders of the Group insurers are members of Jewelers Mutual Holding Company. Jewelers Mutual is headquartered in Neenah, Wisconsin, with other Group offices in Dallas, Texas and Miami, Florida. To learn more, visit