Cubic zirconia

Introduction and Overview of Cubic Zirconia

Cubic zirconia is a cubic crystalline form of zirconium dioxide (ZrO2).
It is a synthesized material that is hard and usually colorless, but can be made in different colors.
It should not be confused with zircon, which is a zirconium silicate.
Cubic zirconia is a cost-effective and durable alternative to diamonds.
Its main competitor as a synthetic gemstone is synthetic moissanite.
Cubic zirconia was discovered in 1937 as a natural counterpart to the synthetic product.
Commercial production of cubic zirconia began in 1976.

Cubic zirconia is crystallographically isometric.
Stabilizers like yttrium or calcium oxide are used to form and maintain cubic crystals.
It has a density between 5.6 and 6.0 g/cm3, about 1.65 times that of diamond.
Cubic zirconia is relatively hard, scoring 8-8.5 on the Mohs scale.
Its refractive index is high at 2.15-2.18, and it exhibits an Adamantine luster.
Cubic zirconia has no cleavage and shows a conchoidal fracture.
It has a high dispersion of 0.058-0.066, exceeding that of diamond.
Under shortwave UV, it typically fluoresces yellow, greenish yellow, or beige.
Colored cubic zirconia stones may exhibit a strong rare earth absorption spectrum.
Due to its high hardness, it is generally considered brittle.

The primary method of synthesis is the skull-melting method.
This method allows for high temperatures and choice of gas atmosphere.
The process involves a cup-shaped crucible surrounded by RF activated copper coils.
Zirconium dioxide mixed with a stabilizer is fed into the cold crucible.
The resulting crystals are formed through controlled crystallization and cooling.
Phase relations in zirconia solid solutions: cubic phase crystallizes first, followed by tetragonal and monoclinic phases.
Concentration of yttrium determines the resulting product (PSZ or monophasic cubic crystals).
Crystals below 14% concentration tend to be opaque, indicating partial phase separation.

Yttrium cubic zirconia (YCZ) is used for windows, lenses, prisms, filters, and laser elements.
YCZ is used as a window material for monitoring corrosive liquids in the chemical industry.
Partially stabilized zirconia has high hardness, shock resistance, low friction coefficient, and high chemical and thermal resistance.
Partially stabilized zirconia is used as a building material in the bio-engineering industry.
It is used to make super-sharp medical scalpels compatible with bio-tissues.
Coating cubic zirconia with a film of diamond-like carbon (DLC) makes it harder and more lustrous.
DLC coating quenches excess fire of cubic zirconia and improves its refractive index.
Vacuum-sputtering a thin layer of precious metal or metal oxides creates an iridescent effect.
Precious metal coatings are not durable compared to the cubic zirconia substrate.
Innovations aim to improve the appearance and properties of cubic zirconia.

Cubic zirconia has a hardness rating of approximately 8 on the Mohs scale, while diamond has a rating of 10.
Cubic zirconia has a higher density than diamond, allowing for differentiation by weight.
Refractive index of cubic zirconia is lower than that of diamond, leading to immersion techniques for identification.
Dispersion of cubic zirconia is higher than that of diamond.
Cut and color of cubic zirconia can differ from diamonds.
Cubic zirconia can reduce demand for conflict diamonds.
De Beers Company held a monopoly on the diamond market and engaged in price-fixing practices.
The price of diamonds continues to increase due to demand in emerging markets.
Cubic zirconia offers a lower-priced alternative for jewelry buyers.
The Kimberley Process aims to deter the trade of conflict diamonds, but is not fully effective in all markets.

Reference	URL
Glossary	https://harryandcojewellery.com.au/blogs/glossary/cubic-zirconia
Wikipedia	http://en.wikipedia.org/wiki/Cubic_zirconia
Wikidata	https://www.wikidata.org/wiki/Q225666
Knowledge Graph	https://www.google.com/search?kgmid=/m/0ghfv