How to Tell if Your Diamond Is Real or Fake - Practical Testing Tips
When buying a diamond, how can you be certain it’s a genuine diamond? To determine whether a diamond is real, the diamond’s physical and optical properties need to be examined to know the difference from a simulant or a diamond look-alike.
Diamonds possess unique characteristics such as exceptional hardness (10 on Mohs scale), high thermal conductivity, and distinct refractive properties. These qualities set them apart from materials like cubic zirconia, moissanite, or glass. Below is exquisite diamond jewelry.
There are several at-home tests like the fog test, dot test, sparkle test, or a diamond tester that can provide preliminary insights, but they are not foolproof. Advanced testing methods conducted by professional gemologists, such as thermal or electrical conductivity testing and spectroscopy will offer greater accuracy and reliability.
We will look at some diamond “substitutes”, followed by some testing methods to help you make a more informed decision about your diamond’s authenticity.
Stones and Gemstones That are Diamond Substitutes or Diamond Simulants
Several gemstones resemble diamonds but are not real diamonds. These stones can be natural or synthetic and vary in their physical and optical properties. Diamond simulants may look like diamonds, but do not have the same chemical or physical properties (i.e. cubic zirconia, moissanite, white sapphire). Below are some common diamond substitutes:
Cubic Zirconia
This synthetic material is best known for affordability and is sometimes used as a substitute as a fake diamond. Cubic zirconia (CZ) is denser than a diamond, will look flawless because it’s synthetic, and is softer and less durable than a diamond. This leaves cubic zirconia prone to scratches and clouding over time. Shown are a ring with cubic zirconia as the center stone and a yellow cubic zirconia and diamond ring.
Moissanite
Most moissanite is lab grown (synthetic). Natural moissanite is extremely rare. The appearance of moissanite is similar to diamonds, with more fire and brilliance under light. It rates 9.25 on the Mohs scale which is less hard than a diamond. Moissanite is more expensive than CZ, but is still much cheaper than diamonds. Featured are moissanite rings:
White Topaz
White topaz is a natural gemstone. It rates a 8.0 for hardness on the Mohs scale. Being it is softer than a diamond, it is prone to scratches, abrasions, and cloudiness over time. White topaz generally have good clarity, but may have natural inclusions. This gemstone is bright and clear but less brilliant than a diamond. It can appear dull with prolonged use without proper care. It is affordable, and is more expensive than CZ. Featured is a lab-grown sapphire with white topaz gemstones.
White Sapphire
White sapphire can be a natural or synthetic stone. It is clear and bright, but lacks the sparkle and fire of diamonds. It is affordable compared to diamonds, but often appears cloudy over time due to scratches (9 on the Mohs scale). Featured is a white gold, white sapphire tennis bracelet and a diamond, white sapphire, and tanzanite necklace.
Lab-Grown Diamonds
Synthetic diamonds are lab-created diamonds which are man made in a laboratory or industrial setting rather than formed naturally. They have the same chemical, physical, and optical properties as natural diamonds, but their origin is artificial.
Synthetic diamonds must be clearly labeled as lab-created, synthetic, or similar to differentiate them from natural diamonds. Certification bodies like GIA or IGI often include the origin of the diamond in their grading reports. Pictured is a yellow gold pear cut lab-created diamond engagement ring.
At-Home Tests
The following are simple tests you can try at home to check for the authenticity of a diamond. There are at-home tests like thermal conductivity testers or simpler methods like the dot test, which can provide quick indications of whether a gemstone may be a diamond, but their accuracy can vary depending on the type of test and specific circumstances.
It should be noted that testing with a loose diamond is more reliable than a mounted gemstone. Also, only doing one test is insufficient for a diagnosis. However, for the most reliable way to learn if your gemstone is a real diamond, the best thing you can do is bring it into a reliable jeweler and let them check it for you.
Fog Test
With a fog test, you will breathe onto the diamond as you would fogging up a mirror. A real diamond clears up almost instantly because diamonds dissipate heat quickly, whereas a fake diamond will stay foggy for a few seconds longer due to slower heat dissipation.
This test is not definitive. It can fail with materials that dissipate heat slower than diamonds, like moissanite, or fail to identify lab-created diamonds.
The Water Test
Using a glass of water, drop the diamond into it. A real diamond will sink to the bottom because it is dense. A fake stone may float or sink more slowly if it’s made of a lighter material like cubic zirconia when using the water test.
Reflections Test
Look at how the light reflects off the diamond. A real diamond should produce a sharp, clear sparkle with a mix of white (brilliance) and rainbow (fire) reflections. A fake diamond may appear dull or overly colorful without the sharp brilliance of a genuine diamond.
Scratch Test
Diamonds are extremely hard and can scratch glass or other hard surfaces without causing damage to the actual gemstone. This test is not always recommended as it could damage the item you are scratching or the gemstone if it is not a diamond.
Dot Test
The dot test is a simple method to help distinguish between a genuine diamond and certain diamond simulants such as cubic zirconia or glass, by evaluating how light interacts with the gemstone. This test is based on the optical property of refraction, which affects how light passes through the stone.
Draw a small dot on a white piece of paper using a pen or marker. Flip the stone upside down so its table (the flat top facet) is resting directly over the dot. The dot will not be visible or will appear highly distorted because real diamonds have a high refractive index which causes light to bend significantly as it passes through. With cubic zirconia or glass the dot will be visible or only slightly distorted.
This test doesn’t work for mounted stones. This test also doesn’t distinguish all simulants. For instance, moissanite or white sapphires have a high refractive index similar to diamond and may pass this test.
Heat Test (Riskier)
Heat the stone with a lighter for about 30-60 seconds, then drop it into cold water. A real diamond remains intact due to its high heat tolerance. A fake diamond may crack or shatter.
UV Light Test
Expose the diamond to UV or blacklight. A real diamond often glows blue under UV light, though not all do. A fake diamond may not fluoresce, or may fluoresce differently.
Sparkle Test
To check a diamond’s sparkle, hold the stone under direct, bright light or near a natural light source. Look for colorful flashes and white light as you move the stone. If your diamond is the real thing, it should have very high brilliance. A simulant may lack brilliance or appear dull in comparison. This test alone cannot confirm whether it is a natural or lab-grown diamond.
Diamond Testers
Consumer grade diamond testers can have a reasonable amount of accuracy for quickly distinguishing diamonds from most common stimulants such as cubic zirconia or glass. However, they have notable limitations especially when it comes to advanced diamond alternatives like moissanite or distinguishing between natural and lab-grown diamonds.
These consumer testers can do thermal conductivity tests (measures how quickly a gemstone dissipates heat) and electrical conductivity tests (measure the stone’s ability to conduct electricity).
Budget model testers may wear out or lose accuracy over time, especially if they lack proper calibration features. They can be prone to false positives or negatives due to poor calibration, dirty gemstones, mounted stones, or small-sized stones which can give inaccurate readings.
Limitations of At-Home Diamond Tests
Moissanite closely mimics the appearance of diamond and can be difficult to differentiate from diamonds using basic tests. A combination of tests or more advanced tools will be needed.
Mounted stones can give inaccurate readings, as the setting may interfere with heat or electricity conductivity tests. It would be unusual for most consumers to have loose diamonds. Very small diamonds or gemstones may be hard to test accurately at home.
While at-home tests are useful for a quick check, they aren’t foolproof. Professional gemologists have access to more advanced tools like the spectroscopy or x-ray testing that can give definitive results, including distinguishing between natural diamonds and synthetic diamonds.
Professional Testing
Gemologists, diamond experts, and jewelers use a combination of scientific tests and advanced tools to determine a diamond’s authenticity. These methods can differentiate mined diamonds from simulants, and can also identify lab-grown diamonds. Testing on a loose diamond or unmounted gemstone will also give more accuracy.
Visual Inspection
An at-home test may suggest using a magnifying glass, but it will not stand up to a professional’s use of a jeweler’s loupe or microscope which have a greater degree of magnification to identify inclusions, growth patterns, or other characteristics unique to natural diamonds.
Genuine diamonds may have irregular inclusions or internal growth patterns. Whereas lab-grown diamonds can have specific growth lines or metallic inclusions and simulants will tend to have uniform clarity or unnatural patterns.
Thermal Conductivity Testing
An industry diamond tester will measure how quickly the stone conducts heat. Diamonds should dissipate heat rapidly as they have high thermal conductivity. This test is effective for identifying simulants like zirconia and glass, but not between diamonds and moissanite, as both have high thermal conductivity. This test will be used in conjunction with the next test listed.
Electrical Conductivity Testing
This test measures the stone’s ability to conduct electricity and is useful for differentiating between moissanite and diamonds. Moissanite conducts electricity whereas natural or lab-grown diamonds do not.
UV Fluorescence Testing
A UV light is used to observe fluorescence which is common in many natural diamonds. This test is not definitive for identifying lab-grown diamonds.
Refractive Index Testing (Sparkle)
A refractometer is used to measure how light bends as it enters the gemstone. The measured stone must be unmounted for precise measurements.
Spectroscopic Analysis
A spectroscope is used to analyze the light absorption and scattering properties of the stone. This test can distinguish natural diamonds from lab-grown ones.
X-Ray Imaging
An x-ray machine is used to determine the stone’s crystalline structure. Diamonds allow x-rays to pass through more easily compared to many simulants. This test doesn’t distinguish between natural and lab-grown diamonds.
Advanced Lab Tests
Instruments like DiamondView, Fourier Transform Infrared Spectroscopy, and Photoluminescence spectroscopy are used to differentiate natural diamonds from lab-grown diamonds.
Density and Specific Gravity Testing
Density meters or hydrostatic weighing are used to measure the density of the stone. Diamonds are high density gemstones. This test needs to be done on loose stones.
Why Professionals Use Multiple Tests
Professionals use multiple tests to determine if a diamond is the real deal. Moissanite requires electrical conductivity testing to differentiate from diamonds. The spectroscopy or UV fluorescence analysis are needed to determine lab-grown diamonds.
Mounted stones require non-invasive methods like x-ray imaging or polarization testing. By combining these methods, professionals ensure an accurate and comprehensive evaluation of a gemstone’s authenticity.
Finally
Testing to determine if a diamond is real involves examining its physical, optical, and conductive properties using various methods. Simple at-home tests can provide basic clues, but lack precision. Having your diamond checked with a professional provides you with more reliable tests and accuracy when they analyze the stone’s unique characteristics. Professional jewelers and gemologists will use multiple tests to ensure a reliable evaluation.
If you want to know if your diamond ring, necklace, bracelet, or inherited jewelry is the real deal, come talk to us. If you are interested in choosing an engagement ring, we can show you gemstone/stone types listed earlier. We are also happy to help you extend your jewelry collection with high-quality rings, necklaces, bracelets, etc.
Our jewelry store professionals at The Estate Watch & Jewelry Company have the experience and expertise that can help you with buying your diamond jewelry. You can check if your jewelry is high quality. If desired, we can help you upgrade your diamond by resetting your ring or upgrading your gemstone. We’d love to see you soon!