How to Know If a Diamond is Real

For you to know if a diamond is real, you need to be familiar with how diamonds are structured and what they’re made of. If you are not familiar with their structure, you might mistake other stones like cubic zirconia or moissanite for diamonds and with that, this post will enlighten you on How To Know If a Diamond is Real.

How To Know If a Diamond is Real
How To Know If a Diamond is Real

Real diamonds have strong refractive qualities, causing light to bounce in various directions instead of a straight line. This is why you won’t be able to see letters or dots through a natural diamond.

In this comprehensive guide, we’ll enlighten you on the easy ways or methods in which you can use to know when a diamond is fake.

How to Tell if a Diamond is Real or Fake

Here’s a simple guide on how to determine if a diamond is real or fake or rather How To Know If a Diamond is Real:

1) Water Test

Fill a standard drinking glass about three-quarters full with water. Gently place the loose diamond into the glass. A real diamond, being denser, will sink to the bottom, while a fake one will either float just below the surface or at the very top.

2) Fog Test

Hold the diamond or ring between two fingers and breathe on it to create a light fog due to moisture and heat. If the fog quickly dissipates, the diamond is real.

If it takes several seconds for the fog to disperse, it’s likely a fake diamond. Real diamonds conduct heat efficiently, causing the fog to disappear rapidly.

3) Check Setting & Mount

If the diamond is in a ring, examine the setting and mount. Real diamonds are typically set in high-quality jewellery, such as white gold, platinum, yellow gold, pave or side-stone settings, and halo setting rings.

Check inside the ring’s centre for markings like 10K, 14K, 18K (indicating gold), or PT and Plat (indicating platinum). Numbers like 585, 770, 900, and 950 also suggest platinum or gold. If you find a “C.Z.” stamp or engraving, the gemstone is cubic zirconia, not a real diamond.

4) Heat the Stone and Check for Shattering

Diamonds are extremely durable and won’t respond much to high heat. To test if a diamond is real using heat, fill a drinking glass with cold water. Use pliers or fireproof gloves to hold the stone.

Heat the stone with a lighter for about 40 seconds, then drop it into the cold water. If it shatters, it’s not a real diamond, as real diamonds are resilient to heat. Weak materials like glass or cubic zirconium will crack due to the quick expansion and contraction of heat.

Imagine a hot dish pulled from an oven and washed immediately—a similar shock can break weak materials. Diamonds, being one of the strongest materials, won’t be affected by this temperature change.

5) UV Light Test

Another way to check if a diamond is real is to place it under a UV light and observe the reaction. Most diamonds emit a blue glow, but not all of them do.

Lack of glow doesn’t necessarily mean it’s fake, as some diamonds don’t react to UV light. Since this test isn’t conclusive, it’s advisable to have a diamond expert or jeweller use advanced equipment for a more accurate assessment.

Testing a Diamond at Home Using Refractivity

When a diamond sparkles, it’s due to its ability to bend and refract light. This is called brilliance. Fake stones like Cubic Zirconia lack this quality.

1) Newspaper/‘Read-Through’ Effect

Place the diamond flat side down on a well-lit newspaper with lots of letters. If you can read the letters, it’s fake. A real diamond refracts light in different directions, making the letters blurry.

Note: This test works best on loose diamonds. If the diamond is already set, consider other tests or consult a diamond expert.

2) The Dot Test

Place a white paper on a flat surface, draw a small dot, and lay the diamond flat side down on it. Look through the pointed end of the diamond onto the paper. If you see a circular reflection, it’s fake. If not, the diamond is real.

Real diamonds refract light powerfully, causing it to bounce in different directions, preventing clear visibility of dots or reflections.

Testing a Diamond at Home Using Reflectivity

Reflectivity is about the amount and quality of light reflected off the stone.

1) Sparkle Test

Hold the diamond under a lamp and observe how light reflects off it. Real diamonds reflect white light exceptionally well, giving off a bright sparkle. They also reflect coloured light (fire) magnificently.

A genuine diamond shows a noticeable difference in both white and coloured light sparkle compared to a fake like Cubic Zirconia.

Expert Techniques to Ensure a Diamond Is Real

While various at-home tests are useful, it’s advised to consult a professional diamond expert for certainty.

1) Inspecting a Diamond with a Loupe

A professional gemologist will use a loupe (a magnifying glass) to look for imperfections (inclusions) within the diamond. Even well-made fake diamonds lack these small imperfections.

2) Using A Thermal Conductivity Probe (Diamond Tester)

A thermal conductivity probe is used to determine how quickly a gemstone disperses heat. Real diamonds, being effective heat conductors, rapidly disperse heat. Slower heat dispersal indicates a fake, though note that moissanites may show similar heat dispersion.

Multiple diamond testers are available, and it’s essential to choose a reliable one.

3) Testing a Real Diamond with High Profile Weighing

Jewellers and gemologists use finely tuned scales for small weight differences. A real diamond weighs less than fakes like Cubic Zirconia. Special carat scales are needed to detect these minute differences. To test, use a fake diamond of similar shape and size as a comparison.

4) Spot a Fake Diamond Using Electricity Conductivity

An electricity conductivity test, performed by a jeweller or gemologist, helps detect a fake diamond. Diamonds conduct electricity better than other stones, including synthetic moissanite. A diamond shows conductivity, while moissanite and cubic zirconia do not.

Testing a Real Diamond vs. Moissanite

Given the increasing prevalence of synthetic moissanite, use jeweller’s tools for an immediate determination of authenticity.

1) Examining Using a Microscope

At 1200x magnification, a jeweller or gemologist scrutinizes the stone for inclusions and differences between real diamonds and moissanite.

2) Get an X-ray Examination

To review the internal molecular qualities of a stone, send it to a professional diamond lab for an X-ray examination. Diamonds are radiolucent, while fakes like cubic zirconia have more radiopaque features.

Is the Scratch Test Reliable To Ensure a Diamond is Real?

The scratch test, once widely used, is not accurate because fakes like cubic zirconia and moissanite are scratch-resistant. Use other tests like thermal conductivity or professional loupe inspection.

How To Spot Other Stones That Aren’t Real Diamonds

1) How to Recognize Synthetic Diamonds

Consult a gemologist for a review as synthetic diamonds have similar chemical and molecular components to natural diamonds. Conductivity tests and high magnification help differentiate them.

2) How to Recognize Cubic Zirconia

Use the sparkle test to gauge sparkle and fire. Cubic zirconias reflect orange-tinted light, weigh more than real diamonds, and lack imperfections.

3) How to Recognize White Sapphire

White sapphires lack the diamond’s signature sparkle and contrast. If the stone appears more blurred in colouring, it’s likely a white sapphire.

4) How to Recognize Moissanite

Moissanite is a convincing fake. An electricity conductivity test helps identify it. Note that the thermal conductivity test is not valid for moissanite.

5) How to Recognize White Topaz

White topaz, though resembling a diamond, is softer and easily scratched. Diamonds won’t have scratches due to their durable composition. Use magnification to check for scratches.


This guide includes various tests, such as the fog test and the thermal conductivity test, that can help determine whether a diamond is genuine.

However, synthetic gemstones can be intricate, so it’s advisable to seek the expertise of a diamond specialist or jeweller to assess any diamonds you already own. These professionals are well-versed in identifying fake diamonds.

If you rely on our diamond education or consult with diamond experts when making a purchase, you won’t encounter difficulties distinguishing between real and fake diamonds.

Every diamond you buy will come with a valid GIA or AGS certificate, and your task is simply to confirm that the diamond matches the details on the certificate.

Well, with this post you now know or have ideas on How To Know If a Diamond is Real.



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