ALL ABOUT CUBIC ZIRCONIA (CZ) -DIAMOND SIMULANT

Cubic zirconia (CZ) -Diamond Simulant

 

The cubic crystalline form of zirconium dioxide (ZrO₂)

The synthesized material is hard and usually colorless, but may be made in a variety of different colors.

It should not be confused with zircon, which is a zirconium silicate(ZrSiO₄).

It is sometimes erroneously called cubic zirconium.

Because of its low cost, durability, and close visual likeness to diamond, lab created cubic zirconia has remained the most gemologically and economically important competitor for diamonds since commercial production began in 1976.

 

HISTORY

Discovered in 1892, the yellowish monoclinic mineral baddeleyite is a natural form of zirconium oxide.

 

On the photo: Baddeleyite from Phalaborwa, South Africa

The high melting point of zirconia (2750 °C or 4976 °F) hinders controlled growth of single crystals.

However, stabilization of cubic zirconium oxide had been realized early on, with the synthetic product stabilized zirconia introduced in 1929. Although cubic, it was in the form of a polycrystalline ceramic: it was used as a refractory material, highly resistant to chemical and thermal attack (up to 2540 °C or 4604 °F)

In 1937, German mineralogists M. V. Stackelberg and K. Chudoba discovered naturally occurring cubic zirconia in the form of microscopic grains included in metamict zircon. This was thought to be a byproduct of the metamictization process, but the two scientists did not think the mineral important enough to give it a formal name. The discovery was confirmed through X-ray diffraction, proving the existence of a natural counterpart to the synthetic product.

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. Its production eventually exceeded that of earlier synthetics, such as synthetic strontium titanate, synthetic rutile, YAG (yttrium aluminiumgarnet) and GGG (gadolinium gallium garnet).

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, an allusion to 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 (an allusion either to the shape of the water-cooled container or to the form of crystals sometimes grown).

They named the jewel Fianit after the institute's name FIAN

(Physical Institute of the Academy of Science), but the name was not used outside of the USSR.

Their breakthrough was published in 1973, and commercial production began in 1976.

 In 1977 cubic zirconia began to be mass-produced in the jewelry marketplace by the Ceres Corporation with crystals stabilized with 94% yttria.

Other major producers include Taiwan Crystal Company Ltd,

Swarovski and ICT inc By 1980 annual global production had reached 60 million carats (12 tonnes) and continued to increase with production reaching around 400 tonnes per year in 1998.

Because the natural form of cubic zirconia is so rare, all cubic zirconia used in jewelry has been synthesized, or created by humans.

Worker monitoring melting zirconium oxide and yttrium oxide in an induction heated "cold crucible" to create cubic zirconia.