Cubic Zirconia Simulated Diamonds

Cubic Zirconia is well known as a substitute for diamond, due to its high hardness and great fire. But in recent years, it has established itself as a gorgeous gem in its own right. CZ is a beautiful synthetic gemstone that is durable and inexpensive and now even comes in any color of the rainbow, making it even more desirable.

Cubic Zirconia is a cubic form of zirconium oxide that is created in a laboratory, thus it is not a mineral. However, it was found naturally occurring once at one site in the 1930's, but has yet to be discovered since then. The mineral with the same chemical composition as CZ, but in the monoclinic crystal system, is baddeleyite.

Synthesized zirconium oxide, cubic zirconia, is hard (8.5 on Mohr's Scale of Hardness), optically flawless and usually colorless, but may be produced with a variety of different colors. The refractive index of CZ is between 2.088 and 2.176, which is very high. Since CZ is transparent, it is often faceted. It can be made in nearly any color and can be faceted into many cuts. Because of its low cost, durability, and close visual likeness to diamond, synthetic cubic zirconia has remained an important diamond simulant since 1976.

To produce CZ, baddeleyite (ZrO2 ) is heated to about 2300 degrees Celsius (almost 5,000 degrees Fahrenheit). This causes the mineral to become isometric. However, this change is not permanent, it reverses upon cooling; which is why a stabilizer must be added to prevent transformation upon cooling. If too much stabilizer is added, it results in a softer, less brilliant product. This requires such high heat that a special radio frequency "skull crucible" must be used to melt the zirconia powder. As the zirconia melts, it leaves a thin shell that remains solid because it is cooled by the water in the copper fingers. As this occurs the zirconia and the stabilizing oxide are added to fill the skull the desired level. The contents are kept molten for several hours to ensure uniformity.

To produce colors, oxides of cerium, copper, titanium, iron, nickel, and many other elements are added also.

History

Cubic Zirconia was discovered in its natural state in 1937 by two German mineralogists, von Stackelberg and Chudoba. It was in a highly metamict zircon given to them by B.W. Anderson. The zircon contained tiny crystals that were determined to be the cubic form of zirconium oxide by x-ray diffraction. The two mineralogists thought so little of their discovery that they did not even give it a name; which is why it is still known by its scientific name, cubic zirconia.

It wasn't until the 1970's, however, that Soviet scientists learned how to grow the crystals in the laboratory. In 1977, it was first marketed under the trade name "Djite." But CZ really took off in the 1980's when Swarovski & Co., a world-renowned Australian producer of leaded crystal, began producing cubic zirconia for mass consumption.
Caring for CZ

Cubic zirconia can be cleaned with any conventional jewelry cleaner or detergent. With such a high hardness and durability, you can use a brush to clean off dirt or oil also. Ultra sonic jewelry cleaners may also be used on CZ and will not damage the stone. However, when using soaps or detergents to clean CZ, one should wipe the jewelry dry thoroughly to avoid residue from the soap leaving a film that will dull the brilliance of the stone. Cubic Zirconia should be cleaned frequently to remove oils from skin that also dull the brilliance of the gem.