Imitations: natural or artificial stones that try to imitate the real ones. Glass or some natural stones (such as spinel or white sapphire) can be used to imitate the diamond. Synthetic stones: stones made up in a laboratory that have the same properties and chemical elements as a natural stone. There are, however, differences between a stone designed in a few months by man against another one in thousands of years under the Earth.
The hardest and brightest synthetic stones: Zirconium oxide, yttrium aluminate, moissanite, strontium titanate, yag, CZ or synthetic rutile.
CZ (Cubic Zirconia or Zirconia)
Duller and milky appearance
No inclusion - Color of D - Z, but bleaches and tarnishes over time
Passes from orange to ultra-violet / orange flash under a microscope
Bad thermal conductor, quickly becomes warm in the hand
More dispersion than in a diamond
Duplication (cloudy effect in the stone)
More fragile than a diamond
Cubic Zirconia - Diamond
Synthetic Moissanite - Diamond
Synthetic diamonds. The Verneuille method is used to produce synthetic rubies since the 19th century. But the first synthetic diamonds were created in the 1950s and were mainly of industrial quality. Gem quality crystals remain small in size. It’s towards the 1990s that the first interesting synthetic diamonds, in terms of weight and quality, made their appearance.
Some treatments, such as the High-Pressure High-Temperature (HPHT) or Chemical Vapor Deposition (CVD), are particularly hard to detect. A total absence of inclusions and the presence of substantially different growth lines could be an index that the gem has received such treatments. The major "diamond culture" factories are located in China, Russia and Canada.
Recognizing a diamond. Several methods can give you clues to identify a real diamond, but only more advanced analysis done by a professional laboratory will inform you with certainty about the nature of the stone.
The straight line. For round brilliant diamonds: draw a straight line on a sheet of paper. Place the diamond table on the line. If you are able to distinguish the line through the stone, it is not a diamond. The 100% light reflection found in a diamond, combined with the complexity of the reflections caused by the ray of light make the observation of the line impossible.
Note that the sparkle of a diamond is seen on the entire stone, including the sides, unlike some counterfeits, such as doublets, which sparkle only from above.
Cold feeling. Pass the diamond on the edge of the lips or on the temple. Diamond being a good thermal conductor, the stone will tend to remain cold. Unlike glass, CZ or plastic.
Blow on the diamond. The vapor evaporates almost instantly. The diamond has no physical or chemical affinity with water and retains neither vapor nor drops of water.
Sandpaper. Rub the diamond on sandpaper. Since it can only be scratched by another diamond, a real one should stay intact.