Published March 18, 2025
Estate Rose Cut Diamond 18K Gold Edwardian Style Link Necklace

When purchasing a diamond, whether it’s part of an engagement ring or another significant piece, it’s essential to ensure you’re getting exactly what you’ve paid for. Finding out that the diamond you thought was real is actually a fake can be devastating, especially when it involves such an important purchase.

How can you tell if a diamond is real? There are several diamond simulations and substitutes available in the market. While some of these have value, others are entirely worthless. This guide will help you understand how to tell if a diamond is real, focusing on key differences, tests, and important gemological details.

What Makes a Real Diamond Different from a Fake One?

To identify a real diamond, you must understand the distinguishing characteristics between diamonds and simulants. Here’s a breakdown of how real diamonds compare to common fakes:

1. Weight and Density

Real diamonds are much denser than most fake stones. While cubic zirconia (CZ) is heavier than diamonds, genuine diamonds are typically denser. This is one of the easiest ways to differentiate between a diamond and a simulant.

2. Composition: Carbon vs. Glass and Silicon

Real diamonds are made entirely of carbon atoms arranged in a crystal lattice, making them the hardest natural substance. On the other hand, fake diamonds like CZ are made from glass and silicon. This difference in composition is what leads to the unique properties of diamonds.

3. Light Refraction and Transparency

Real diamonds refract light in such a way that the images seen through them are obscured. Fake diamonds, such as CZ, look clearer and more transparent. This occurs because diamonds have a unique optical property that makes them scatter light in a spectrum of colors.

4. Edges and Durability

Diamonds have sharp, well-defined edges. Fake diamonds, on the other hand, often have rounded edges due to their lack of durability. Real diamonds are also far more resistant to scratches compared to simulants like moissanite and cubic zirconia.

5. Inclusions and Imperfections

One of the most notable features of a real diamond is its natural imperfections, known as inclusions. These imperfections are often microscopic, but they can be observed under magnification. Fake diamonds, however, are flawless and lack these natural features. This is a reliable indicator when determining authenticity.

6. UV Fluorescence

Real diamonds typically emit a blue glow when exposed to ultraviolet (UV) light, although not all diamonds exhibit this feature. Fake diamonds, such as CZ, tend to emit a yellow glow under UV light. This is one of the most common ways to distinguish between a real diamond and a simulant.

7. The Setting

Another way to determine whether a diamond is real is by inspecting the setting. Real diamonds are often set in high-quality precious metals, such as gold (10K, 14K, or 18K) or platinum (marked PT or Plat). If the stone is set in a low-quality metal or has a CZ marking, it is likely a fake.

Read More at What if your diamond isn’t real?

Home Tests to Check if a Diamond is Real

If you’re unsure about the authenticity of your diamond, you can perform several simple tests at home to help confirm whether it’s genuine.

1. Sandpaper Test

Diamonds are one of the hardest substances on Earth, so if your stone is real, it won’t scratch easily. Try rubbing the stone against a piece of sandpaper. A genuine diamond will not be scratched, while a fake diamond will show signs of wear.

2. Read-Through Test

Place the diamond over a newspaper or text. If the diamond is real, you will not be able to read the text clearly because diamonds scatter light in multiple directions. Fake diamonds like cubic zirconia will allow you to read the text more easily.

3. Water Test

For loose stones, fill a glass with water and drop the stone into it. If the diamond sinks to the bottom, it’s real. Fake diamonds, such as cubic zirconia, may float or remain at the top due to differences in density.

4. Sparkle Test

Natural diamonds emit a greyish sparkle, while fake stones like cubic zirconia have a highly colored, iridescent sparkle. If the stone emits an unnatural, rainbow-colored sparkle, it’s likely a fake.

5. Breath Test

Breathe on the diamond and observe how it reacts. A real diamond will clear its fog almost instantly because of its high thermal conductivity, while a fake diamond will take several seconds to clear.

6. Dot Test

Draw a dot on a piece of white paper and place the diamond on it, flat side down. If you can see the dot through the pointed end of the stone, it is a fake. A real diamond refracts light and prevents you from seeing the dot through the stone.

7. Heat Test

Diamonds can withstand extreme temperature changes. Heat the stone under a flame for 40 seconds, then drop it into a glass of ice water. If the stone shatters, it is likely cubic zirconia or another fake type of diamond.

8. Thermal Conductivity Tester

A thermal conductivity tester can measure how quickly heat disperses through the diamond. Genuine diamonds conduct heat much faster than simulants like cubic zirconia. This tool can be purchased online for as little as $20.

Common Diamond Simulants and How to Identify Them

While cubic zirconia is the most common fake diamond, other stones can be mistaken for diamonds, even by gemologists. Here’s a list of some other common diamond simulants:

1. Moissanite

Moissanite is harder to identify than cubic zirconia. It has a higher refractive index than diamonds, which causes it to sparkle more intensely. An electrical conductivity test can differentiate moissanite from diamonds, as moissanite has a different conductivity profile.

2. White Sapphires

White sapphires lack the brilliance and dispersion of diamonds. They have blurred coloring with no distinct dark and light areas, unlike diamonds. While they are hard and durable, they are not as brilliant as diamonds.

3. White Topaz

White topaz is softer than diamonds and will scratch easily. It also lacks the dispersion and brilliance that a diamond has.

4. Lab-Grown Diamonds

Lab-grown diamonds are chemically identical to natural diamonds but are created in a controlled environment. The controversy surrounding lab-grown diamonds stems from their rapid production, which sometimes causes confusion in the market. Lab-grown diamonds are often sold at a lower price but are still real diamonds, created with the same carbon lattice structure.

What Should You Do If You’re Still Unsure About Your Diamond?

If you still have doubts after performing these tests, the best course of action is to take your diamond to a professional gemologist for an in-depth examination. A gemologist can use specialized equipment to analyze the stone and provide a definitive answer regarding its authenticity.

Visit the American Gem Society

At Dover Jewelry & Diamonds, we stand by our 31-year reputation for offering 100% authentic diamonds. We provide third-party certificates showing the 4Cs—color, cut, clarity, and carat weight—verified by reputable gemological organizations such as the Gemological Institute of America (GIA) and the American Gem Society (AGS).

Conclusion

In today’s market, authenticating a diamond has never been more challenging. With the advancements in technology, the floodgates have opened to a variety of diamond simulations and substitutes, making it difficult to know what is truly authentic. From cubic zirconia to moissanite, and even lab-grown diamonds, the lines between real and fake have become increasingly blurred. Unfortunately, this has also created opportunities for misrepresentation, especially on various platforms where diamonds may not be accurately disclosed.

As a buyer, it’s essential to do your due diligence before making such an important investment. Always ensure that you’re purchasing from a trusted source that provides certified, authentic diamonds. If you’re still uncertain, a professional gemologist can offer clarity.

One comforting fact to remember is that vintage and antique diamonds are not lab-grown. Their history, craftsmanship, and authenticity stand the test of time. At Dover Jewelry, we pride ourselves on offering only genuine, certified diamonds—no imitations, no confusion—so you can feel confident in your purchase.

Learn More at How to Identify and Authenticate Your Vintage Jewelry

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