General Gem Information:
Cubic Zirconia is relatively new to the gemstone world. It was first discovered in the 1920s by a couple of German mineralogists. Chemically, it is a cubic form of zirconium oxide, making it different from Zircon (which is made up of Zirconium Silicate). Cubic Zirconia became popular as a diamond substitute in jewelry in the 1970s when Soviet scientists discovered how to grow it in a lab setting. It is typically not found in nature, so CZ are often virtually flawless. CZ are almost always transparent and often mimic the look of a high-quality diamond. In fact, the similarity in appearances are so vast that they often need to be magnified to distinguish the two.
Unlike Zircon, Zirconia is also a very hard stone, and is not brittle. While not matching the perfect 10 of a diamond on Moh's scale, it comes close at 8.5.
Because this gem is almost exclusively lab created, there really aren't superstitions about it.
Notations on Wearing Zircon:
The most important link between Zirconia and her gemstone counterpart is the idea of a cheap substitute for diamonds. Because Sailormoon is often represented by diamonds, the name points out that Zirconia, while a queen who is also flashy, is not the same thing. One could also further follow the train of thought since Queen Nehellenia acts through Zirconia for a large portion of the Dream arc of the manga and the SuperS season of the anime, that she is very much an imposter, and has less quality as ruler of the Dead Moon than Usagi does as ruler of the Moon Kingdom.