CZ: DIAMONDS ARE BEING COUNTERFEITED | EN

Everybody more or less knows the cubic zirconium (CZ). To this day, it is the best imitation of a diamond. Precisions about this substitute for the eternal gem.

Distinction Cut to the right proportions, cubic zirconium, at the beginning, was difficult to identify Above all when it was set. Even the professionals got caught ! Heavier than the diamond, with a specific weight of 5,6 to 6 against 3,5 for the diamond, zirconium is smaller, for the same weight, than the diamond when we are talking about surface, a one carat diamond is more or less the equivalent of a cubic zirconium of around two carats. Classed between 8 and 8,5 on Mohs's ladder of hardness, the stone is nevertheless identifiable already worn, it shows edges of the separation of damaged facets. Its refraction index is 2.18, which places it very close to the diamond whose index is 2.41 Unlike the eternal gem, the rondist of the ZC are shiny and semi polished, and the polishing lines are visible. Where the diamond retains its shine, the copy becomes dull when rubbed. Under the magnifying glass, it displays slightly rounded edges, due to the cotton buff wheel polishing As for diamond, it displays edges as fine as razor blades. Another element which enables to tell the difference: the finish. The stars and halefis are perfectly symmetrical on a diamond. They remain haphazard on the copies.
 
Manufacturing cubic zirconium, which requires high temperatures, is a problem for the formation of crystal. There are several patents. The manufacturing principle is the formation of crystal during solidification of a magma in a container composed of zirconium oxide and its additives, so as to obtain a mass comparable to a thick crust and including the CZ crystals. Amongst the patents, the FFWWenckus one consists in making use of a melting pot composed of copper tubes, arranged in a circle and cooled through a complex system. In between the copper tubes there are fine spaces, surrounded by the water cooling system in copper batteries activated by 4 MHz radio frequency with a power of 100 kW Such spaces make it possible for the radio frequency to send its energy in the tank, initially filled with zirconium powder and stabilising agent. The powder, at room temperature, works as an electric insulation and only reaches the heating process when a few metallic zirconium crystals are being added. When adjacent zirconium is added to the metal component, electric conduction makes the whole melt in a few minutes. Reacting with the oxygen in the air, metallic zirconium produces even more zirconium. The whole melts then and the centre of the magma crumbles down, after cooling, crystallising. It entails shapeless and lengthy crystal pieces.
 
It is possible to colour the CZs with a weak dye to which are added titanium, iron, copper, chromium, holmium, ervium, etc. It is even possible to find diamond coloured standards in cubic zirconium from D to L This system is of particular interest to the jeweller who then does not have to invest large amounts in the standards of at least 050 carat diamonds.
 
At the end of the 1990s, the industry went through a panic wave when the Ceres firm created the synthetic Moissanite stone. Yet this stone remains a great deal more expensive and, at the end of the day, the CZ, brighter, remains the best imitation of diamond. Today it is being used to set silver jewellery, and even gold jewellery.

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