Estate Rose Cut Diamond 18K Gold Edwardian Style Link Necklace

How to tell if a diamond is real or not

When you purchase a diamond, you want to make sure you are getting what you’ve paid for – especially if it is part of an engagement ring. Starting out your married life together with a ring you later discover is a fake is devastating.

There are several diamond simulations and substitutes on the market. Some of these have value, whilst others are worthless.

Here are some basic differences:

  • Real diamonds are much heavier and denser than most fake ones, although cubic zirconia (CZ) is heavier than diamonds.
  • Real diamonds are made of carbon, fake ones from glass and silicon.
  • Real diamonds refract light; images seen through diamonds are obscured but fake diamonds look clearer and more transparent.
  • Real diamonds have sharp edges. Fake ones will have rounded edges.
  • Real diamonds have imperfections or inclusions; fake ones have none.
  • Real diamonds emit a blue glow in ultraviolet light; fake diamonds emit a yellow glow.
  • Real diamonds are less sparkly; fake ones look like high-end glass.
  • Check the setting. Does it have a gold (10K, 14K or 18K) or platinum mark (PT or Plat)? If the stone is fake, it will probably not be set in high-quality precious metal. If it is cubic zirconia, it should have a CZ marking.


If you are suspicious about the authenticity of a diamond you have already purchased, it is advisable to have it examined by a professional who can conduct tests with specialized equipment.  There are some home tests you can do, however:

  • Sandpaper Test. Rub the stone with the gritty side of a piece of sandpaper. A diamond is one of the hardest substances in the world, so if it is real, it will not scratch. A fake diamond will!
  • Read-through Test. Try and read a newspaper through the diamond. If it is real, you won’t be able to read a word. A fake diamond will let you read the words.
  • Water Test (if your stone is loose) Fill a glass with water and drop the stone to the bottom of the glass. If it sinks, it is real. If it floats on the top or near the surface of the water, it is fake.
  • Sparkle Test. Natural diamonds have a greyish sparkle to them. Fake stones such as cubic zirconia emit a highly colored, iridescent sparkle.
  • Breath test. Breathe on the stone and see if it fogs up. If it does, and the fog goes away immediately, it is likely a real diamond. If it takes several seconds to clear, it is probably fake. Diamonds quickly disperse the heat from your breath.
  • Dot Test. Draw a dot on a piece of white paper. Put the stone onto the dot, flat side down. If you can see the dot through the pointed end of the stone, it is fake. If the dot is not visible, the stone is real. This is because a real diamond refracts light which bounces off in different directions instead of in a straight line.
  • Heat Test. Hold the stone under a flame for 40 seconds. Drop it into a glass of ice-cold water. If the stone shatters, it is probably cubic zirconia or another fake type of diamond. Diamonds can withstand extreme changes in temperature.
  • Diamond Thermal Conductivity Tester/Probe. This is a relatively inexpensive tool you can buy online for as little as $20. Diamonds are very effective heat conductors, so when heat is transmitted through the tester it will disperse quickly if it is real. If the heat is dispersed at a slow rate, the diamond is not real. The tester has a needle-like tip that you place against the stone which beeps or indicates on a display if you have a real diamond.
  • Black/UV Light Test. When you place a real diamond underneath ultraviolet light, most of them, but not all, will turn blue. A fake diamond, on the other hand, will rarely look blue under a black or UV light.

Here are a few tips on recognizing diamond simulants:

  • Cubic Zirconia has a highly colored, iridescent sparkle that looks fake. It has no inclusions and is heavier than a real diamond.
  • White Sapphires have blurred coloring with no distinctive dark and light areas.
  • Moissanite is more difficult to recognize. You’ll need a professional to conduct an electrical conductivity test.
  • White Topaz has a softer exterior than diamond, so it will scratch easily.

The best way to avoid the nagging feeling that you may have been cheated is to be very careful about WHERE you buy your diamond in the first place. Check out your jeweler carefully. Look at their customer reviews. Check out their BBB rating, if they have one.

At Dover Jewelry & Diamonds, we stand by our unparalleled, 31-year reputation. We have an A+ BBB rating, and our customer reviews are exceptional.

When you buy diamond jewelry from us, you will receive a third-party certificate showing the 4Cs of your diamond’s qualitycolor, cut, clarity and carat weight, as verified by the Gemological Institute of America (GIA) or the American Gem Society (AGS) for example.

Whether you are shopping for a special engagement ring, such as our vintage three-stone Old European Cut diamond and platinum 3.00-carat beauty (I-J color and VS2 Clarity),

or an eternity band, such as our extraordinary Asscher cut ring, with 104 diamonds graded F-G color and VVS2-VS1.

or perhaps special occasion jewelry, for example, a pair of vintage Art Deco diamond and blue sapphire earrings,

.. you can rest assured that our diamonds have been certified as 100% authentic.

The bottom line is – check out your retailer thoroughly before buying from them to avoid a costly mistake.

It is well worth it.