4 Easy Ways To Tell If You Have A Real or Fake Diamond

Imagine you’re strolling down a sidewalk and your eye catches the sparkle of something that appears to be a diamond… could this be your lucky day?!  Is it real and how can you tell?

Round Diamond vs. Cubic Zirconia

Round Diamond vs. Cubic Zirconia

The best thing to do is to take the gemstone to a jeweler who has the experience and equipment necessary to verify if the stone is a real, natural diamond (after you’ve tried to identify the rightful owner of course!).   But what if you want to test out your own detective skills first?  Here are a few tests you can perform, keeping in mind that no one test is conclusive:

  1. Check the ‘Read-Through’ effect:   If the stone is loose or unmounted you can turn it upside down on a printed piece of paper.  If you cannot read the text through the stone it may be a real diamond.  If the letters are visible, it is probably not a genuine diamond.  This test works best with properly cut round brilliant stone.
  2. Try the ‘Fog Test’ (or ‘Breath Test’):  Since diamonds are efficient heat conductors, once you breathe on a real diamond the fog should disperse immediately.  If the stone is a fake diamond the top will stay foggy for a few seconds longer.  This test works best with a clean stone.
  3. Test with a Thermal Conductivity Probe (also known as a diamond tester):  As mentioned, diamonds are efficient heat conductors.  Using the thermal test separates most fake diamonds from real diamonds by detecting the rate the stone disperses heat.  This test works on most gemstones, with an exception being synthetic moissanite.  A synthetic moissanite stone may register as a real diamond with the thermal test.
  4. Moissanite Doubling

    Moissanite Doubling

    Use Magnification:  If you have access to a jeweler’s loupe or microscope there are many observations you can make to help determine if the stone is a real diamond.  If the stone passes the heat test, you will want to confirm that it is a real diamond and not a moissanite.  Using magnification, look at the gemstone through one of the bezel or star facets on the crown.  If the stone shows doubling, which means it looks like there are two of each facet line, then it is probably a moissanite.  If you see only one of each facet line (singly refractive) and it passed the heat test then it may be a natural diamond.

Beware that other materials such as Cubic Zirconia (CZ) are also singly refractive.  You can also use magnification to identify a real diamond from a CZ by looking at the girdle (the narrow edge around the circumference of the stone).  Real diamonds will have either a frosted, grainy look or tiny facets around the girdle whereas a CZ will be completely smooth.

Another observation you can make using magnification is whether or not the stone has natural inclusions.  Real diamonds typically have some sort of inclusion(s) that naturally occurred during its growth process.  Cubic Zirconia and other man-made materials are produced in a controlled environment and typically do not exhibit any inclusions.

If you are shopping for diamond jewelry here are a few questions you can ask to confirm the stone you are buying is a real diamond:

  • Does the stone have a diamond report or certificate from the Gemological Institute of America (GIA), European Gemological Laboratory (EGL) or other laboratory?
  • Is the diamond laser inscribed with an identifying number or other unique mark on the girdle?
  • Ask to have the inclusions pointed out to you… most real diamonds have some sort of visible inclusions under magnification.

Above all, it is always important to work with a jeweler who you trust and has your best interests in mind.  Who knows, maybe that sparkly little stone that caught your eye will turn out to be real!

Note:  CZ and moissanite are cited as examples because they are the two most prevalent diamond simulants.  Please be aware that there are also other simulants available on the market. 

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