Zirconium in its pure form is actually a chemical element that can be found in the periodic table. For those interested it has an Atomic Number of 40. However, although a naturally occurring element and metal, it is not found in its pure form and instead forms a part of several minerals, the most common being Zirconium Silicate which is mined heavily in the USA, Australia, India, Brazil and Russia.
Zirconium was discovered in 1789 by the German chemist Martin Klaproth, although he did not manage to isolate the element. This was achieved in 1824 by Jons Jakob Berzelius, a Swedish chemist, with pure Zirconium first prepared in 1914. Pure Zirconium is a greyish-white metal that is used in a wide range of industrial processes including heavy use by the Nuclear industry due to its hardness, heat resistance and non-reactive properties. These characteristics also help to make it ideal for jewellery.
Obviously a grey-white metal would hardly make an ideal substitute diamond so the raw material needs processing to produce the clarity required for jewellery. To do this high purity zirconium oxide powders, stabilized with magnesium and calcium, are heated to very high temperatures until they melt together, crystalising and clarifying on cooling to produce a clear, hard substance with properties similar to diamond and suitable for use in jewellery. During this process small amounts of other chemicals can also be added to produce different coloured crystals.
Although ‘close’ to real diamond, there are obviously small different between Cubic Zirconia and diamond including hardness and brilliance. The naked eye finds it hard to differentiate between the two, however true diamond does have an increased refractive index (the ability to refract a ray of light into its component colours). Cubic Zirconia (CZ) has a refractive index of around 2.16, whereas diamond has an index value of 2.42. As I say, although this is difficult to pickup with the naked eye it does mean that true diamond will always ‘sparkle’ just that little bit more when properly cut.