Identifying Real Diamonds

How to tell if your diamond is authentic

Stefano Navi Lab Grown Diamond Stud Earrings in Box

There are few purchases in life more important than a diamond – particularly if it is for an engagement ring. Apart from the obvious desire to get what you’ve paid for, an engagement diamond is a symbol of your future lives together as a married couple. It is full of meaning and importance for you both, so you will want to make sure it is an authentic stone. 

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

Real diamonds - both lab-grown and natural mined- will stand out from fake diamonds. Here are some basic differences between real and fake diamonds:   

  • Real diamonds are much heavier and have higher density than most fake ones, although cubic zirconia is heavier than diamond.
  • Real diamonds are made from carbon, fake ones from glass and silicon.
  • Real diamonds refract light more than fake ones; 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 a high-quality precious metal. If it is a cubic zirconia, it should have a CZ marking.

There are some home tests you can do, however:   

  1. 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!
  2. 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.
  3. 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 a fake. 
  4. Sparkle Test. Natural diamonds have a greyish sparkle to them. Fake stones such as cubic zirconia emit a highly colored, iridescent sparkle. 
  5. 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. 
  6. 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.  
  7. Heat Test. Hold the stone with a set of plyers and heat it up under a flame for 40 seconds. Drop it into a glass of ice-cold water. If the stone shatters, it is probably a cubic zirconia or another fake type of diamond. Diamonds are among the strongest substances on earth, so they can easily withstand extreme changes in temperature. 
  8. Diamond Thermal Conductivity Tester/Probe. This is a relatively inexpensive tool you can buy online for as little as $20. It tests the thermal conductivity of your stone and will tell you if it is a real diamond or not. 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. 
  9. Black/UV Light Test. When you place a real diamond underneath an 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 electricity 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.

Unfortunately, there are unscrupulous retailers, particularly those who sell online, who try to make a fast buck from unsuspecting purchasers who are not sufficiently educated about diamonds to understand what they are buying. 

The bottom line is. Buyer beware! 

Where you buy your diamond makes a huge difference.  It is important to purchase from a reputable jeweler offering third-party verified diamonds, which have been tested for their 4Cs of quality – color, cut, clarity and carat weight by the Gemological Institute of America (GIA) or the International Gemological Institute (IGI), for example. 

When you buy through Stefano Navi, you will receive a certificate showing the quality - and therefore the authenticity - of your diamond.  We stand by our reputation to provide the highest quality, sustainable, conflict-free, lab-created diamonds on the market.

We invite you to choose your perfect, real diamond. If you are suspicious about the authenticity of a diamond you may have already purchased, it is advisable to have it examined by a professional who can conduct tests with specialized equipment.  

Shop certified lab-grown diamond engagement rings here