How Do I Tell If a Diamond Is Real?

In the world of precious gemstones, diamonds stand unrivaled in their beauty and allure. Their value and desirability have led to the creation of numerous synthetic and imitation diamonds in the market. Suppose you find yourself questioning the authenticity of a diamond. Fear not. This article will guide you through reliable methods to determine whether a diamond is real or fake.

Visual Inspection

A visual examination can offer initial clues about a diamond’s authenticity. Look closely at the stone for imperfections or blemishes. Genuine diamonds often possess tiny internal flaws known as inclusions or external flaws called blemishes.

These can be observed using a jeweler’s loupe or microscope. Additionally, natural diamonds tend to have sharp edges and well-defined facets, whereas fake diamonds may exhibit rounded or blurred edges.

  • Imperfections: Genuine diamonds often have natural imperfections, known as inclusions or blemishes. These can be seen under magnification and indicate the diamond’s authenticity.
  • Clarity characteristics: Real diamonds have unique clarity characteristics, such as tiny internal crystals, feathers, or clouds. You can observe these features using a jeweler’s loupe or microscope and compare them to known diamond characteristics.
  • Edge sharpness: Authentic diamonds typically have sharp, well-defined edges due to their precise cutting. On the other hand, fake diamonds may have rounded or blurred edges, indicating a lack of craftsmanship.

Sparkle and Refraction

Diamonds possess remarkable sparkle and brilliance due to their high refractive index. Place the diamond under a light source to assess this and observe how it interacts with light. Genuine diamonds disperse light, creating flashes of white and colored light known as fire. 

The sparkle should be vibrant, with light bouncing around within the diamond. In contrast, fake diamonds or diamond simulants may lack the same level of brilliance.

  • Fire and brilliance: Genuine diamonds disperse light and exhibit flashes of white and colored light, known as fire. When you move the diamond under a light source, observe the intensity and pattern of the sparkle. Real diamonds have a vibrant and captivating display.
  • Refractive index: Diamonds have a high refractive index, meaning they bend and reflect light more than other gemstones. This property contributes to their exceptional brilliance. If a stone lacks the mesmerizing sparkle and displays dullness, it may be a fake diamond or an inferior quality stone.

Diamond Tester

Utilizing a diamond tester can be an effective method to differentiate real diamonds from their imitations. These electronic devices measure a diamond’s thermal conductivity. Since diamonds have high thermal conductivity, the tester will typically display a positive result. 

However, it’s important to note that specific synthetic diamonds or diamond simulants can produce similar results so additional tests may be necessary for confirmation.

  • Thermal conductivity: Diamond testers rely on the principle that real diamonds have high thermal conductivity. The device measures the diamond’s ability to conduct heat. When the tester comes into contact with a real diamond, it typically produces a positive reading.
  • Limitations: It’s important to note that some synthetic diamonds or diamond simulants, such as moissanite, can exhibit similar thermal conductivity to real diamonds. Therefore, while a diamond tester can provide an initial indication, further evaluation may be necessary.

Fog Test

One simple yet popular test involves breathing on the diamond’s surface. Real diamonds disperse heat rapidly, causing the fog from your breath to dissipate almost instantly. 

On the other hand, fake diamonds or moissanite, which have similar thermal properties, may retain the fog for a few seconds longer. Although this test can provide a clue, it should not be solely relied upon to determine a diamond’s authenticity.

  • Rapid fog dissipation: When you breathe on a real diamond, the fog from your breath should instantly dissipate. This occurs because diamonds disperse heat quickly. If the fog lingers on the stone’s surface for an extended period, it may indicate that it is not a real diamond.
  • Similarities with simulants: It’s worth noting that certain diamond simulants, such as cubic zirconia, can also exhibit rapid fog dissipation. Therefore, while the fog test can be a helpful clue, it should not be solely relied upon for definitive authentication.

Seeking Professional Evaluation

When in doubt, it is always advisable to consult a reputable jeweler or gemologist for a professional evaluation. These experts possess the knowledge, expertise, and specialized equipment to assess diamonds accurately. 

They can conduct thorough examinations, including advanced tests such as spectroscopy or microscopy, to provide a definitive answer regarding a diamond’s authenticity.

  • Expertise and equipment: Professionals in the field possess the necessary knowledge, expertise, and specialized equipment to evaluate diamonds accurately. They can conduct advanced tests, such as spectroscopy or microscopy, to precisely determine a diamond’s authenticity.
  • In-depth examination: Jewelers and gemologists will perform a thorough examination of the diamond, taking into account various factors such as its physical properties, optical characteristics, and potential synthetic or imitations. 


Identifying whether a diamond is real or fake can be fascinating yet challenging. By combining visual inspection, tests such as diamond testers or the fog test, and seeking professional evaluation when needed, you can increase your confidence in determining a diamond’s authenticity. 

While these methods can offer valuable insights, advanced synthetic diamonds or expertly crafted imitations may require more sophisticated techniques to detect.


How can I visually determine if a diamond is real?

  • Look for imperfections like inclusions or blemishes, common in natural diamonds.
  • Examine the diamond’s clarity characteristics using a jeweler’s loupe or microscope.
  • Check for sharp, well-defined edges, as genuine diamonds are precisely cut.

Can the sparkle of a diamond indicate its authenticity?

Real diamonds exhibit exceptional sparkle and brilliance due to their high refractive index.

  • Look for flashes of white and colored light, known as fire, when moving the diamond under a light source.
  • Lackluster or dull sparkle may suggest a fake or lower-quality stone.

Are diamond testers reliable for determining authenticity?

  • Diamond testers can provide a quick initial indication of a diamond’s authenticity.
  • They measure a diamond’s thermal conductivity, which is typically high in real diamonds.
  • However, specific synthetic diamonds or diamond simulants may produce similar results, requiring additional tests for confirmation.
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