Real Diamonds vs. Fake Diamonds

The following tests can help you determine if a stone is a real diamond, i.e. natural or lab-grown, or a fake diamond, i.e. moissanite, cubic zirconia, zircon, white topaz or white sapphire:

  1. Position the stone at the contact point of an electronic diamond tester. The tester does not react if the diamond is a fake; a beep sounds and an indicator lights up if the diamond is real.
  2. In a common heat test conducted by many jewelry stores, a fake diamond will heat up while a real diamond quickly disperses the heat.
  3. Cubic zirconia and other fake diamonds typically weigh from 40%-70% more than what a real diamond with the same “carat size” would weigh according to a gemstone size-weight chart.
  4. A fake diamond sends out a rainbow like effervescence while a real diamond emits a characteristic white shine, which is commonly called the diamond’s “brilliance.”
  5. Fog up the stone with your breath. On a real diamond, the fog will evaporate almost immediately. A fake diamond will fog up for 2-4 seconds the first time you breath out, and with each exhaled breath the stone fogs up more as condensation builds up.
  6. Check to see if your stone scratches by rubbing it on the surface of sandpaper. If the stone gets scratched, it is a fake. Caution: Do not attempt to bang against the stone with a hammer. While the surface of a real diamond cannot be scratched, it can be chipped.
  7. Turn a loose (un-mounted) stone upside down and place it on a newspaper. If you can read right through it, or even decipher distorted smudge marks from the newspaper print, the stone is a fake. However, take into account that a real diamond that is poorly cut, i.e. lacking proportion, will also enable you to read the newspaper through it.
  8. Real diamonds are flawed; fakes present an illusion of flawlessness, masking the fact that they are not real. Most real diamonds will show inclusions (internal imperfections) through a jeweler’s loupe or a 1200x microscope. Cubic zirconia, when fashioned to perfection, does not contain any inclusions. Lab-grown diamonds, which pass all the other tests, also lack the imperfections that are inherent in most natural diamonds.
  9. Place the stone under a UV light or a black light. A real diamond will reflect medium-dark blue fluorescence. This test is not conclusive as the absence of blue does not necessarily prove that the stone is a fake – it may just be a better quality diamond. Moissanite may reflect green, yellow or gray fluorescence under UV light.
  10. Ask your jeweler for a detailed certificate from a recognized independent gemological laboratory to authenticate the genuineness of your stone.