How to Tell if a Diamond is Real
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With so many diamond alternatives on the market — cubic zirconia, moissanite, white sapphire, and more — it's understandable to want to verify whether a stone is a genuine diamond. Here are the most reliable ways to tell if a diamond is real, and why buying certified diamonds from a trusted jeweler like Gallo Jewelry is always your best protection.
The Fog Test
Breathe on the diamond as you would to fog up a mirror. A real diamond disperses heat instantly and won't fog up, or if it does, the fog clears almost immediately. A fake stone like cubic zirconia will stay fogged for several seconds because it doesn't conduct heat as efficiently.
The Water Test
Drop the stone into a glass of water. Real diamonds have a high density and will sink immediately to the bottom. Many fakes, like glass, will also sink — so this test is more of an elimination tool than definitive proof.
The Light Reflection Test
Look at the diamond under a light source. A real diamond reflects light in various shades of gray inside the stone (brilliance). If you see rainbow colors inside the stone like a prism, it may be a glass or crystal imitation.
The Newspaper Test
Place the stone upside down on a newspaper or printed text. If you can read through the stone, it's likely not a diamond — real diamonds refract light so strongly that letters are not visible through them.
UV Light Test
Expose the stone to a UV (black) light. About 30% of diamonds fluoresce blue under UV light. However, this test is not conclusive — not all real diamonds fluoresce, and some fakes may also react.
Professional Testing
The only truly definitive way to verify a diamond is through professional testing with a diamond tester (which measures thermal or electrical conductivity) or through laboratory certification. At Gallo Jewelry, every diamond comes with a GIA or IGI certificate — the most trusted documentation of a diamond's authenticity and quality.
When you shop with us, you never have to guess. Every stone is verified, certified, and guaranteed. Shop our certified diamonds.