How To Know If a Diamond Is Real Or Fake?

One of the first questions that everyone asks when they see a diamond is whether it is real or fake. In this article, we will teach you everything you need to know to determine if a diamond is real.

Benjamin Khordipour is a GIA-registered Gemologist, author, and lecturer on diamonds, gemstones, and vintage jewelry.

Diamond Authentification Guide

Authenticating a diamond isn’t rocket science, and there are many at-home techniques that you can employ to get a good idea if a stone is a diamond or not.

Even if a stone looks white and sparkles like a diamond, it can be many other things: moissanite, cubic zirconia, lab diamond, and glass.

Please Note: The following techniques are only guides and at-home suggestions for determining if a diamond is legit. If you want to know for certain, you will need to show it to a professional.

1. Hot Breath Diamond Method

Diamond Setting: Loose and Mounted
Equipment Needed: None
Effective Results: 30%. Won’t work for lab-grown diamonds

This is the easiest way to determine if a diamond is fake. We recommend it to all the people who consult with us, and we encourage you to try it before trying anything else.

Simply take the diamond and breathe on top of it. If the mist and fog disappear quickly, it is possible that it’s a diamond. If the mist stays on the stone and takes over 2-3 seconds to disappear, it is quite likely that you’re looking at a fake diamond.

Diamonds are extremely effective at conducting heat, which, along with their hardness, is why they are very suitable for industrial cutting processes. Fake materials like CZ and glass are actually quite poor conductors of heat, so a simple test will give you some idea as to whether you have a diamond or an imitation.

Make sure your diamond is at room temperature and breathe on it.

Once you have completed your test, don’t forget to clean the diamond.

2. The Newspaper Diamond Test

Diamond Setting: Loose and Mounted
Equipment Needed: Newspaper (or any paper with writing on it)
Effective Results: 40%. Won’t work on lab-grown diamonds

Like the previous diamond authentication test, the newspaper test is wildly easy.

Lay the diamond on top of a newspaper with its table facing the text (as shown below) and then try to read the text through the diamond. If the letters show through the diamond as if it were glass, the stone is likely not a diamond.

This trick will also work if the diamond is set in a mounting, but it may be a little hard to get enough like to see the letters because the mounting may get in the way.

Important Note: There are a few possible reasons that the diamond may still show clear text through it, so make sure that you show the diamond to an expert before you determine that it is fake.

3. The Water and Diamond Test

Diamond Setting: Only loose diamonds
Equipment Needed: Cup of room temperature water
Effective Results: 20%

This test is one of the least effective methods because it won’t eliminate most fakes, but the good part of this test is that it will eliminate the fakes with absolute certainty.

Fill a cup with room-temperature water and drop the loose stone into the cup. If the “gemstone” floats and doesn’t sink, it is undoubtedly a fake gemstone.

As you can imagine, many fake diamonds will also sink. It is for that reason that this technique doesn’t establish stones as diamonds but merely eliminates fraud very quickly.

4. Diamond Heating Authentication Method

Diamond Setting: Only loose diamonds
Equipment Needed: Tongs, gloves, and a lighter
Effective Results: 40%

Again, this test is good for most fakes but should only be undertaken with extreme care. Ideally, wear heat-safe gloves to avoid injury. Please avoid this test altogether if you are not comfortable with it.

Hold the loose diamond with prongs. With fireproof gloves, grip the stone tightly and expose it to a lighter or another flame for about 45 seconds. Drop the heated stone into a glass of cold water, and if the stone fractures or shatters, it is not a diamond. If no reaction is seen, then the diamond is genuine.

Important Note: Do not try this method if the diamond is set into a mounting of any kind! Additionally, if the diamond is experiencing any form of existing structural damage, giving it this test may cause critical harm.

5. Finding the Certification Number

Diamond Setting: Loose and Mounted
Equipment Needed: Cellphone
Effective Results: 90%

Many diamonds will have been certified sometime in the past, and many of the certification companies will have lasered a certification number onto the side of the diamond. This even applies to antique diamonds that were certified at some later point.

Typically, you will need a jeweler’s loupe (magnifying glass) to see the numbers. The numbers are tiny, and you will need to search hard to find them. We recommend, though, just using your phone camera and putting it to x10 zoom. If you have zoom and lens attachments, that will make it even easier.

Make sure that you place the diamond or diamond ring on a flat and solid surface, and then aim your camera toward the girdle of the diamond.

Once you find the numbers, input those numbers into the certification database (like the GIA, for example), and you will know everything about your gemstone.

6. Finding Inclusions inside the Diamond

Diamond Setting: Loose and Mounted
Equipment Needed: Jeweler Loupe, magnifying glass, or cell phone
Effective Results: 80%

Almost all natural diamonds have inclusions, and although inclusions aren’t desirable in diamonds, they are a fantastic way to determine the authenticity of a diamond.

Clean the outside of the diamond very well, and then take a jeweler’s loupe or put your diamond on high zoom and search for inclusions. If you notice black dots, white dots, lines, or clouds inside the diamond, you will know that it is likely a real diamond.

It could still be a lab-grown diamond, and for that, you’ll need to send it in to be tested by an expert. However, lab-grown diamonds usually have far fewer inclusions than real diamonds.

7. Use a Commercial Diamond Tester

Diamond Setting: Loose and Mounted
Equipment Needed: Jeweler Loupe, magnifying glass, or cell phone
Effective Results: 80%

Although they are far from perfect, the cheap diamond testers that are all over Tiktok will actually work to eliminate many fakes. We recommend using them even though the results are far from definitive.

A diamond tester will cost approximately $25 or so, and they are fun to use. Link to Amazon.

Just be warned that these cheap testers will give false positives and false negatives and will not be able to determine many different simulants and lab-grown diamonds.

8. Autheticate the Mounting of the Diamond

Diamond Setting: Mounted
Equipment Needed: N/A
Effective Results: 90%

A great way to authenticate a diamond is by authenticating the mounting that the diamond is sitting inside. If the mounting has provenance, there is a good chance that the stone inside shares its story.

To learn how to authenticate vintage jewelry or designer jewelry, click here to read our full guide.

9. Show the Diamond to an Expert Jeweler

Diamond Setting: Loose and Mounting
Equipment Needed: N/A
Effective Results: 100%

If all the above fails or doesn’t give you definitive results, bringing the diamond to an expert jeweler is the best option.

An expert jeweler will have professional equipment and be able to give you a definitive opinion on the status of the stone. He’ll be able to tell you if the stone is a diamond, lab-grown diamond, CZ, or moissanite.

Finding a Reliable Jeweler to Examine Diamond

As you can imagine at this point in the article, not all jewelers will be able to determine with complete accuracy if a diamond is genuine or not. Additionally, not all jewelers are honest and reliable.

Here’s our advice on how to find a jeweler who can examine your diamond to determine if it’s real or not.

• Get advice from friends and family of jewelers that they trust.
• Check Google Reviews, Yelp, and BBB for reviews on your diamond seller.
• Ask for certifications (that contain diamond inclusion maps) and appraisals.
• See if he can provide you with other companies who can recommend him.

Different Types of Fake Diamonds

There are many options for fake diamonds. Here are the most common culprits.

• Cubic Zirconia (CZ): A synthetic gemstone that mimics the appearance of diamonds.
• Lab-Grown Diamonds: Carbon-based diamonds made in a lab. Read our full opinion on lab-grown diamonds.
• Moissanite: Nearly as hard as diamonds. Moissanite is a lab-grown crystal.
• White Sapphire: Naturally occurring, white sapphires lack the fire and brilliance of diamonds but offer a hard, durable, and more affordable alternative.
• Glass: Easily shaped and colored, glass can mimic various gemstones, including diamonds, but lacks their hardness and sparkle. It is also known as “paste”.
• Synthetic Rutile: A high-refractive material with a diamond-like luster, but softer texture and unique rainbow dispersion.
• Synthetic Garnet: Some varieties of synthetic garnet can be used to imitate diamonds, but they typically exhibit different optical properties and are softer.
• High-Lead Content Glass (Rhinestones): Often used in costume jewelry, these glass pieces sparkle brilliantly under light but lack the hardness and durability of real diamonds.
• Gypsum: While not commonly used as a diamond substitute due to its softness, gypsum can be cut and polished to mimic the appearance of a variety of gemstones in low-cost jewelry.

How to Know if You’re Buying a Real Diamond?

As a buyer, there are a few large warnings that should trigger your suspicion. These warnings won’t tell you that the diamond is fake but rather should spur you to investigate.

• A seller that doesn’t have solid reviews and a solid reputation
• If a diamond is valued at a level that seems too good to be true, it almost certainly will be. Even assuming it isn’t fake and appears to be of good color and clarity, a suspiciously low price will often mean the diamond is stolen, which brings more problems than you’ll ever want to encounter.
• Lack of documentation and certifications
• A seller who is pushing too hard
• No return policy

Either way, diamond values are easily searchable on the internet, so as long as you can establish the 4Cs of the stone, you can quickly assess the approximate value.

If it is significantly lower than the going rate, walk away.

Final Thoughts

Provenance is a great way to know if your diamond is real, but if it isn’t available, a certificate of appraisal is the next best thing. If all else fails, the tests above may help to eliminate some doubts, but a professional assessment will always be the ultimate way to check if your diamond is natural or imitation.