Beautiful Cubic Zirconia
Cubic Zirconia – usually called ‘CZ’ – is becoming more and more popular as a wonderful gem to use in all types of jewelry. Let’s learn a little more about this gemstone.
Cubic zirconia is the cubic crystalline form of zirconium dioxide. The synthesized material is hard, optically flawless and usually colorless, but is also available in a variety of different colors. It should not be confused with zircon, which is a zirconium silicate. It is sometimes erroneously called ‘cubic zirconium’. Because of it is so inexpensive, it is durable, and looks so much like a diamond, synthetic cubic zirconia has remained the most gemologically and economically important competitor for diamonds since 1976. It is sometimes marketed under the brand name ‘Diamonique’.
Cubic zirconia is relatively hard, at about 8 on the Mohs scale— slightly harder than most semi-precious natural gems. Because of its high hardness, it is generally considered brittle. It is also very bright and sparkles beautifully – close to the level of a real diamond. Under shortwave UV cubic zirconia typically fluoresces a yellow, greenish yellow or “beige”. Under longwave UV the effect is greatly diminished, with a whitish glow sometimes being seen. Colored stones may show a strong, complex spectrum.
And, now for a bit of history. Discovered in 1892, the yellowish monoclinic mineral baddeleyite is a natural form of zirconium oxide. It has little economic importance because of its rarity. Many years ago, as with the majority of grown diamond substitutes, the idea of producing single-crystal cubic zirconia arose in the minds of scientists seeking a new and versatile material for use in lasers and other optical applications. Some of the earliest research into controlled single-crystal growth of cubic zirconia occurred in 1960s France, much work being done by Y. Roulin and R. Collongues. This technique involved molten zirconia being contained within a thin shell of still-solid zirconia, with crystal growth from the melt: The process was named cold crucible, because of the system of water cooling used. Though promising, these attempts yielded only small crystals.
Later, Soviet scientists under V. V. Osiko at the Lebedev Physical Institute in Moscow perfected the technique, which was then named skull crucible, and they named the jewel Fianit after the institutes name, but the name was not used outside of the USSR. Their breakthrough was published in 1973, and commercial production began in 1976. By 1980 annual global production had reached 50 million carats. The Soviet-perfected skull crucible is still used today, with little variation. Water-filled copper pipes provide a cup-shaped scaffold in which the zirconia feed powder is packed, the whole contraption being wrapped with radio frequency induction coils running perpendicular to the copper pipes. A stabilizer, typically calcium oxide, is mixed with the feed powder.
But, enough of all this technical stuff. I doubt that anyone reading this would be interested in making their own cubic zirconia. Instead, we like to look at it and enjoy collecting it in its many beautiful forms in so many wonderful pieces of jewelry.
