As we continue on our exploration of the differences between natural diamonds and cubic zirconias(CZ), we will now examine the toughness, hardness and dispersion of each of these stones. It is also important to talk about cleanliness as it is often a red flag for the experienced jeweller out to spot an imposter. [1]
Cleanliness is Not Next to Godliness
When discussing cleanliness of a diamond, this is not in reference to whether or not the stone is dirty, but rather the inside appearance of the stone. Natural diamonds gain much of their unique attributes from the inclusions within the stone. These natural features are found in natural minerals – like diamonds – and do not necessarily signal a flawed stone. A completely flawless stone under a 10-power jeweller’s loupe is most likely a cubic zirconia as the natural diamond version would be out of the financial reach of many a consumer.
How Tough is the Stone?
While cubic zirconias are known to outweigh natural diamonds nearly two to one, diamonds dominate when it comes to toughness. A material’s ability to resist breakage from a forceful impact is its toughness and diamonds tend to stand alone. In fact, the toughness of natural diamonds has been measured as 3.4 MN m-3/2; much stronger than the cubic zirconia stone, which tends to be more brittle than a natural diamond. A CZ stone can be scratched by other stones, while a diamond can only be scratched by other diamonds. [2]
Which Stone is Most Hardy?
Believe it or not, there is an abundance of conflicting information regarding the hardness of natural diamonds. It’s possible the confusion rests in the misunderstanding that this hardness is in reference to a natural mineral as diamonds are the hardest known natural material. [3] In examining the Mohs scale of hardness, natural diamonds score a 10, while the cubic zirconia is significantly softer, yet still respectfully hard, at an 8.5 rating.[4]
Dispersion – the Trick of the Eye
Dispersion is one area where the cubic zirconia is known to trick even the gemstone savvy customer. Dispersion occurs as a result of the gem’s refractive index, or how much a beam of light will bend, based on the direction in which it is passes between two different optical densities. In more basic language, dispersion is the breaking up of light into its spectral colors. A CZ stone has more dispersive power than a natural diamond – a 0.060 vs. 0.044 – creating more color and fire. Even with this difference, a CZ still cannot match the breathtaking brilliance of a natural diamond. [5]
While the toughness, hardness, dispersion and even cleanliness of the two stones are important to understand in the examination of the differences between cubic zirconias and natural diamonds; it could easily be the trip into the science of the creation of each of these gems that is the most fascinating. Check out our next post as we travel back in time.
[1] http://www.gottrocks.com/chat-cz.htm
[2] http://en.wikipedia.org/wiki/Diamond
[3] http://www.diffen.com/difference/Cubic_Zirconia_vs_Diamond
[4] http://www.hsn.com/cubic-zirconia-guide_at-4579_xa.aspx
[5] http://en.wikipedia.org/wiki/Cubic_zirconia
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