How to Identify a Genuine Diamond


Since the cubic zirconia was engineered and began mass production in 1977, it has become increasingly difficult for the lay person to accurately assess whether a “diamond” is genuine or not.  The human eye alone can not be fully trusted.  As such, there are numerous methods that can be used in determining a diamond’s authenticity, from simple tricks one can perform at home to the most sophisticated procedures employed by professional gemologists – like the friendly and helpful ones with excellent penmanship working at Diamond Lighthouse. (Learn More)

If the diamond in question is mounted, meaning encased in a setting, there are a few easy practices you can use.

1.The “Fog” Method.  For this, hold the “diamond” next to your mouth and breath warm air on it.  If when you look at the stone it remains foggy,  then odds are that it is not a real diamond.  Real diamonds instantly dissipate the heat from your breath, whether it’s minty fresh or not.


2.Inspect the setting and mount: a real diamond typically will be set in actual gold, silver or other precious metal …not hard plastic or a finely shaped paper clip.  If there is an inscription stating the karat of the gold (a minimum of 10), or “PT”, “Plat” (indicating platinum), then you are on the right track.  If there is a “CZ”, then that means you have the dreaded cubic zirconia on your hands and should just cry.

3.Take a deeper look with a jeweler’s Loupe.  When viewing a diamond through the magnification of the loupe, you may see small spots, known as “inclusions” in the stone (along with slightly discolored areas).  When a diamond naturally forms, trace minerals often become trapped inside of it.  When one is man made in a lab, there usually are no specks in it, as the environment is “dirt free.”  In the extreme rare circumstance that you have a diamond with no inclusions or discoloration, then you have a “flawless” diamond – that means you’re rich and should immediately jump in the air and yell “Yay!”


When the diamond you are testing is unmounted, there are several other ways you can check its validity it at home.

1.What gives a diamond its brilliance and shine is its degree of refractivity (the profound bending of light passing through it).  Simply put, the higher the refractive index, the more it sparkles.  To test this, you can use the “Newspaper Method.”  Just place the stone face (facet) down on a piece of newsprint.  If you can easily read a letter through the stone, then light is not really being refracted through it, hence it most likely is not real.  Any letters would be smudged and unreadable through an authentic diamond, as if you were reading the newspaper while drunk.


2.Observance of reflectivity.  When looking at light through a stone, impostors (and exceptionally low quality diamonds) will reflect rays of all colors (like the spectrum of an unhappy rainbow).  Real diamonds will reflect, much like the controversial novel, shades of gray.  The shafts of light emanating from a real diamond will be especially intense.  A great way to administer all these tests is to keep a glass stone handy, for comparison.  If you don’t have a glass stone around, then you need more fake jewelry in your life.

3.The “Water” Test.  True diamonds are heavy, due to their incredibly high density.  When dropped in a glass of water, they will sink to the bottom.  Pseudo diamonds will lazily float about, revealing their counterfeit nature.

4.The “Fire” Test.  Apply an open flame to the stone (don’t worry, if it’s real it will be totally fine) and then drop it into cold water.  Glass and quartz will just shatter from the quick expansion and then condensing of its molecules.  Real diamonds can easily withstand this.  Obviously, do not use this test if you like the aesthetic appearance of the stone; diamonds may be forever, but quartz can be nice for a while.

Lastly, if your stone is accompanied by a valid certificate of appraisal from any of the respected diamond grading authorities, specifically, the GIA, then you can be certain you have a real diamond.  Unless it’s a phony certificate…

This next section will detail how professionals in the diamond business accurately test for bona fide diamonds.  

Before utilizing the vast array of tools that gemologists such as the ones working at Diamond Lighthouse employ, these experts will first do a “blind test.”  With many years of expertise, they can assess if a diamond is true or not due to its “color zoning” (impurities in color), faceting, and softness (if a stone is heavily worn it most often is not a diamond).  Next, they move on to the following instruments for the further extraction of the diamond’s details.


1.The “Heat Probe” Test.  This works in identifying diamonds by testing the duration that the stone holds heat for (aka: “Thermal Tester”, which will indicate either “natural” or “synthetic”).  Again, since diamonds have such a high density, heat passes through them quite quickly.

2.The Mohs test of hardness.  This is a scale gemologists use, where each pure mineral is assigned a number from 1 to 10, designating hardness.  For instance, talc is the softest at 1, and diamonds are the hardest at 10.  White Topaz can easily be confused for diamond, however topaz only has a hardness of 8 (as does CZ).  Silly Putty has a -7 rating.


3.One substance which mimics diamonds quite astoundingly is moissanite.  One of the  only ways to distinguish diamond from moissanite with the naked eye, is that moissanite will refract light in a rainbow pattern (but not in a lackluster way, like glass – moissanite does so brilliantly).  Yet for actual proof, a more elaborate device must be used: The “Combination Tester.”  Here a very intricate and specific tool (an electrical conductivity tester) is used to see if the stone is diamond or moissanite.

4. Currently, the single most sophisticated tool at any gemologist’s disposal is the Sarin Machine (such as the one used in house at Diamond Lighthouse). This machine costs approximately $50,000, including the software.  This is a large electro-imaging device that is primarily used in diagnosing all the specific properties of a rough diamond.  With the most cutting edge and innovative technology, it produces a 3-D image of the diamond (highlighting all inclusions) and shows precisely where cuts could be made (along with polishing) for optimal diamond brilliance and value.  The most rudimentary usage of this highly complicated machine would be to assess the basic properties of a stone, ruling whether it is real or not.  Also, it can do your taxes, give guidance regarding your love life and predict the future.  (Learn More)



The best gemologists working in the business today are the in-house, certified experts employed right here at Diamond Lighthouse.  With over 30 years of experience in the field, they will be able to provide you with the most precise and fully comprehensive evaluation of your diamond.  Carefully scrutinizing all of its infinitesimally minute properties, they will give you the most accurate appraisal you could find anywhere.  All of this expertise translates to phenomenal care in the handling of your diamond and ultimately the maximum sale price for you.  It is now time for you to be fully educated, and compensated.


-Joe Leone


Leave a Reply

Your email address will not be published. Required fields are marked *