How To Tell If A Diamond Is Real

Natural diamond has been for centuries the King of gemstones, fascinating mankind with its unique physical and visual properties. Diamonds have always been precious throughout the whole human history. This explains the fact that for decades many has sought alternatives to natural diamonds by creating “look-alike” imitations (Gemological Institute of America uses the term: simulants) which are significantly less expensive and more recently, “duplicates” with creating synthetic diamonds in laboratories.

But how to tell if a diamond is real and of a natural origin?

The best answer is to send the stone to a reputable gemological laboratory in order to be tested and graded.

However, to protect yourself from misconceptions and not to be easily fooled, it is important to be aware of some basic information and means of identification of a diamond. The unique features of the diamond as exceptional hardness, durability, light reflectivity (brilliance) and dispersion (fire) distinguish the stone from other gems.

Let’s have a look at the most popular simulants for diamonds in the market: cubic zirconia (CZ), synthetic moissanite (silicon carbide), white sapphire and glass. All the mentioned simulants differ significantly from the diamond and therefore they display diagnostic properties by which can be recognised with standard gem testing techniques, observations under magnification and the commercially available “diamond testers” on the market.

Some of the diagnostic properties could be the lower hardness of the simulants that are recognised by a lot of abraded surfaces on the stone (for example glass), the exceptional brilliance of the diamonds compared to the other stones (CZ), the extreme double refraction (the synthetic moissanite) compared to the single refractive diamond, and many others of which professionals are well aware.


Natural diamond (left), and various diamond simulants: (inner left to right) synthetic rutile, gadolinium gallium garnet (or GGG), synthetic spinel, strontium titanate, synthetic corundum, yittrium aluminum garnet (or YAG), and colorless zircon.

Natural diamond (left), and (inner left to right), laboratory grown moissanite in the near colorless to greenish range.

The “hot topic” today, however is the discussion for the synthetic diamonds, and particularly their disclosure. As we have already mentioned synthetic diamonds are man-made diamonds with essentially the same chemical and optical properties as natural ones. However unlike naturals, which grow and reside in the earth for millions of years, synthetic diamonds are grown in laboratories over a very short period of time – between two or three weeks, or even less. There exists two processes for creating synthetic diamonds – HPHT (High Pressure High Temperature) and CVD (Chemical Vapor Deposition), out of which the CVD synthetics are much more difficult to be detected.

Since the synthetic diamonds have essentially the same properties as the natural ones, it is basically impossible to be distinguished only by observation even by an experienced gemologist. The most secure way is the stones to be tested in a well-equipped gem lab with modern technology for recognizing several diagnostic features of the synthetics that prove their nature of creating. Our advice is to ask always for a professional advice and require full disclosure of the diamond before you buy.

Last but not least, as consumers we should be aware that on the market exist natural diamonds which have been treated and the best practices oblige the seller to reveal this information as treatments should significantly decrease the price.

Popular treatments today are laser drilling, fracture filling (injecting glass filler in the diamond to improve clarity characteristics), irradiation, diamond’s color enhancing. For all the above mentioned treatments is necessary a laboratory equipment and very experienced professional “eye” to observe them.

Whether to choose a natural diamond or synthetic one, moissanite, white sapphire or any other colorless stones is a matter of choice, but you should be always precisely informed what you are buying.