Cubic zirconia

related topics
{acid, form, water}
{@card@, make, design}
{theory, work, human}
{system, computer, user}
{specie, animal, plant}
{math, energy, light}
{company, market, business}

Cubic zirconia (or CZ) is the cubic crystalline form of zirconium dioxide (ZrO2). The synthesized material is hard, optically flawless 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, 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". Its main competition as a synthetic gemstone is the more recently cultivated material, synthetic moissanite.

Contents

Technical aspects

Cubic zirconia is crystallographically isometric, an important attribute of a would-be diamond simulant. During synthesis zirconium oxide would naturally form monoclinic crystals, its stable form under normal atmospheric conditions. A stabilizer is required for cubic crystals to form, and remain stable at ordinary temperatures; this may be typically either yttrium or calcium oxide, the amount of stabilizer used depending on the many recipes of individual manufacturers. Therefore the physical and optical properties of synthesized CZ vary, all values being ranges.

It is a dense substance, with a specific gravity between 5.6 and 6.0 — at least 1.6 times that of diamond. Cubic zirconia is relatively hard, at about 8 on the Mohs scale— slightly harder than most semi-precious natural gems.[1] Its refractive index is high at 2.15–2.18 (B-G interval, compared to 2.42 for diamonds) and its luster is adamantine. Its dispersion is very high at 0.058–0.066, exceeding that of diamond (0.044). Cubic zirconia has no cleavage and exhibits a conchoidal fracture. Because of its high hardness, it is generally considered brittle.

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 rare earth absorption spectrum.

Full article ▸

related documents
Phosgene
Ziegler-Natta catalyst
Beta sheet
Southern blot
Alum
Carbon-14
Denaturation (biochemistry)
Solder
Nuclear technology
Gel
Alcohol dehydrogenase
Pyroxene
Electron counting
Phosphor
Heme
Solvation
Carbonic acid
Neon
Sintering
Borax
Nucleolus
Mica
Thallium
Organic acid
Roentgenium
Biopolymer
Carboxylic acid
Chloroform
Endoplasmic reticulum
Island of stability