This guide provides comprehensive diamond test methods to help you determine whether a diamond is authentic. While there are several at home tests you can perform, a professional test is critical for absolute certainty of your diamond’s authenticity.
What Does a Real Diamond Look Like?
A real diamond displays certain qualities that set it apart. Diamonds reflect light in a unique way due to their high refractive index. When light hits a genuine diamond, it scatters to create a bright white sparkle called brilliance. In contrast, imitation stones like cubic zirconia or glass often appear dull.
A real diamond also has sharp facet edges. When closely examined, a diamond’s cuts and angles should appear crisp and precise, contributing to its overall sparkle. In contrast, imitation stones often display rounded or poorly cut facets.
Additionally, real diamonds may have inclusions—tiny internal imperfections formed during the diamond’s creation. Imitation stones tend to be flawless.
What Is a Fake Diamond?
A fake diamond, also known as a diamond simulant, is a stone that mimics the appearance of a real diamond but does not have the same chemical, physical, or optical properties. While lab diamonds and natural diamonds are real diamonds as they share the same structure, fake diamonds like cubic zirconia do not.
How to Tell a Real Diamond by Looking at It
The easiest way to tell if a diamond is real is by looking at its sparkle. As mentioned, real diamonds have unparalleled brilliance, characterized by bright white light reflections. If the stone’s shine appears muted or too colorful (with excessive rainbow-like reflections), it might be an imitation.
How to Tell if a Diamond is Real: At-Home Test Methods
There are a few simple, at-home tests that can provide a general sense for whether a stone is a real diamond or not. However, these methods are not foolproof, and we recommend visiting a jeweler for professional testing.
1. Flashlight Test
To tell if a diamond is real with a flashlight involves observing how the stone refracts light. Shine a flashlight directly at the diamond. A real diamond will reflect white light brilliantly, while a fake stone may not reflect as intensely or at all.
2. Sunlight Test
Real diamonds in sunlight exhibit a stunning display of brilliance. Take the gem outside or by a window on a sunny day and observe its reflection. A real diamond will produce bright flashes of white light, accompanied by subtle rainbows.
3. Mirror Test
The mirror test involves placing the stone in front of a mirror to see how it reflects light. Hold the diamond at different angles while facing the mirror. A genuine diamond will scatter light intensely, casting strong reflections.
4. Setting Test
For diamonds set in jewelry, real diamonds are often mounted in high-quality settings like gold or platinum. Check for a hallmark stamp, such as 14K, 18K, or PT, which indicates valuable metal.
5. Water Test
For the water test, fill a glass with water and carefully drop the loose stone in. A real diamond, being denser than most imitations, will sink to the bottom. If the stone floats or stays suspended, it’s likely not a diamond.
6. Fog Test
The fog test is based on the heat-conducting properties of diamonds. Breathe very lightly on the diamond, creating a light layer of fog. A real diamond will disperse heat rapidly, so the fog should clear almost immediately. If the fog lingers for more than a second, it’s likely an imitation.
7. UV Light Test
When exposed to ultraviolet (UV) light, some diamonds emit a glow called fluorescence. While not definitive, this UV light test can indicate authenticity for diamonds that naturally fluoresce. However, lack of fluorescence doesn’t necessarily mean a stone is fake, as some real diamonds don’t fluoresce at all.
8. Dot Test
The dot test can help distinguish a diamond from glass or cubic zirconia. Draw a small dot on a piece of paper and place the diamond flat on top. Look directly down through the stone. If you see the dot clearly, the stone is likely an imitation. A real diamond’s high refractive index will scatter light, making it impossible to see the dot clearly.
The Best Way to Tell if a Diamond is Real
While at-home tests can provide helpful insight, the most reliable way to determine if a diamond is real is through professional testing and official certification.
1. Diamond Certificate
The most authoritative way to verify a diamond’s authenticity is with a diamond certificate from a reputable gemological laboratory like GIA (Gemological Institute of America). These certificates provide detailed information about the diamond’s characteristics and most importantly, its authenticity.
2. Diamond Tester
Jewelers use a professional diamond tester tool that tests thermal conductivity to differentiate a real diamond from fakes. Diamonds disperse heat quickly, unlike many imitations. A diamond tester will indicate whether the stone conducts heat in the way a diamond should, offering a highly reliable assessment.
3. Magnifying Glass Test
A professional jeweler can inspect your diamond using a professional-grade magnifying glass, also known as a loupe. Under 10x magnification, a jeweler will check for natural inclusions or imperfections, which are common in real diamonds. They will also assess the stone’s facet sharpness and overall appearance.
4. Weight Test
Diamonds have a specific density, so comparing the stone’s weight to a genuine diamond of the same size can help identify fakes. Stones like cubic zirconia tend to weigh more than diamonds of the same size. Jewelers use precision scales to measure the difference, ensuring an accurate assessment.
Interested in learning more about diamonds? Check out our other Diamond Guides: Diamond Cut, Diamond Clarity, Diamond Carat, Diamond Color, Diamond Shape, Lab Grown Diamonds, Moissanite vs. Diamond, Moissanite vs. Lab Diamond, Cubic Zirconia vs. Lab Diamond, How Are Lab Grown Diamonds Made?, MM to Carat