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Differences between Diamonds and Cubic Zirconia (CZ)

Know Exact Differences Between Diamonds and Cubic Zirconia (CZ)

Diamonds and cubic zirconia differ in many aspects. Diamonds are the best conductors of heat; whereas, cubic zirconia are thermal insulators, i.e., heat cannot pass through them.
Ningthoujam Sandhyarani
Last Updated: Mar 17, 2018
Cubic zirconia are man-made gems that closely resemble the properties of diamonds. To a layman, both the gems look quite similar. However, professional gemologists can differentiate between them easily. Let's take a look at the differences between these two gemstones.
Diamonds and Cubic Zirconia (CZ)
Diamonds are an allotrope (structurally different forms of the same element) of carbon. To be more precise, they are made up of carbon atoms that are arranged in a specific manner. Though they are found naturally (in mines), man-made diamonds are also available. Cultured varieties are a type of synthetic diamonds, produced under extremely high temperature and pressure conditions.
The compositional material of cubic zirconia is totally different from that of diamonds. As the name suggests, it is made from zirconium dioxide (ZrO2) and has a cubic crystalline form.
Diamonds, whether natural or man-made, are the hardest substances found on earth. According to Mohs scale of mineral hardness, these gems are rated 10, with their absolute hardness value being 1600.
The rating of cubic zirconia with reference to Mohs hardness scale is 8.5, with the absolute hardness value between 200 to 400. It is found that diamonds are about 500 times harder than cubic zirconia.
Shape and color:
Natural diamonds are always associated with some irregularities and imputities in their structure, which impart color. A pure natural diamond is colorless and very rare. In comparison to this, synthetic ones are flawless; rather structural imperfections are imparted in order to simulate the natural ones. Synthesizing colored varieties of these gems, is far cheaper than producing colorless diamonds, as the former ones take less time to grow.
In case of cubic zirconia, structural perfections can be made during the manufacturing process. They can be made colorless, to appear quite similar to pure diamonds. Different colored gemstones of this type are also available in the market.
Diamonds are lightweight as compared to cubic zirconia. The weight of the latter one is about 1.75 times than that of diamonds. To understand better, let's take an example of a one-carat diamond; cubic zirconia of the same size will weigh 1.75 carats.
Diamonds are more bright in comparison to cubic zirconia. It is due to the fact that their refractive index is 2.41, whereas that of the latter is 2.17. Cubic zirconia is also shows more vivid play of colors, as its dispersive power (0.060) is higher than that of diamonds (0.044).
Diamonds have cleavage planes and are found to be more brittle in particular orientations; whereas, cubic zirconia do not have any cleavage planes.
Thus, knowing these intricate differences will certainly help you in identifying these precious gemstones.
Pile of diamonds
Pile of diamonds of various sizes