THE FANCY FAKE

Not to be scoffed at, the cubic zirconia first went into production in the mid-1970s, and since then its popularity has skyrocketed thanks to its likeness to diamonds – so much so that it now stands as its main competitor.

Cubic zirconia (CZ) is the result of a man-made chemical process where zirconium dioxide is synthesised into its crystal form. The material is hard, with a Mohs’ scale rating of 8–8.5. This means that while they are harder than quartz, they are not quite on par with diamonds (10) or semi-precious gems such as rubies (9). They have a refractive index of 2.15–

2.18 (diamonds are 2.42).

CZ and diamonds can appear identical (they can also be produced in the same various colours, such as blue and pink) with the only noticeable disparity being a difference in weight. However, while diamonds conduct heat,

CZ insulates heat. It is this quality that jewellers use to identify the two materials, by way of the Wenckus’ identification method.

Like a diamond, CZ has industrial utility, used as part of the prism and laser technologies. Thanks to its chemical stability, the material is also used to house and view corrosive substances.

Something to remember is that CZ is not the same as a synthetic diamond. Synthetic diamonds are the result of a high demand for rough stones and have been around longer than CZ (the earliest reported experiments date back to the early 19th century). There are a number of methods to produce a synthetic stone, but one of the most common methods is a high-pressure, high-temperature (HPHT) process, in which yellow diamonds are synthesised either via a belt or cubic press. Impurities in nitrogen, the gas that’s used in the synthesising process, is responsible for the yellow colour. Despite them being man-made, synthetic diamonds can still fetch a hefty price.