s
Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

CUBIC ZIRCONIA


CUBIC ZIRCONIA, or PHIANITE (Phianit—Phianite—‘ианит), after the abbreviation of the Physical Inst. of the Acad. of Science named after Lebedev in Moscow, Russia, where they received this synthetic oxide for the first time. In Western gemology, it is called cubic zirconia, CZ, or zirconia.

Composition & Properties. Synthetic zirconium oxide – ZrO2, cubic system. Hardness 8-8.5. Density 5.6-5.9. Diamond luster. Fragile. In the composition it is an analogue of baddeleyite – monoclinic ZrO2, and in structure – that one of tazheranite, a rare natural oxide of zirconium, titanium and calcium. Tazheranite was discovered in Russia in Pribaikalia, in calciphyres of the Tazheranskiy alkali massif in 1969. Phianite is an artificial crystalline material, unstable under the room temperature. As a stabilizing admixture to it they use about 10% of Y2O3. Such compounds can be also produced on the base of hafnium oxide.

In Russia, phianite was synthesized in the middle of 1960-s, and the industrial production of it was opened in 1972. Crystallization of phianite is made in the process of slow cooling of the melt, received with the method of skull casting. It is diathermic heating and melting in a cold container, i.e. in its own hard covering. As a result, they receive an ingot up to 6 kg. weight consisting of an aggregate of monocrystals up to 8 cm. long. They can be colorless or colored in different tones. The color depends on admixtures: chromium – olive-green, cobalt – violet, copper – yellow, other tones are received with admixtures of vanadium, titanium, rare earth elements and others. In the U.S.A., phianites of 24 colors have been producing in the industrial scale since 1976. They are used for the imitation of brilliants and other gems. At that, tints of blue and emerald-green tone are produced in Russia and in the U.S.A. only. Besides, phianites can be black, bi-colored and with the alexandrite effect, there are also non-transparent colored varieties. At the faceting, the crown of phianite is made with an increased table facet to strengthen the play of light and the play of color or the effect of fire in the gem. The Switzerland analogue of phianite – djevalite is stabilized with CaO, or with MgO, Y2O3, and Yb2O3 up to 15%. It has been producing by the firm Jevahirjan in the industrial scale since 1975. In the U.S.A., this material is known under the trade name diamonesque, and its variety is produced under the trade name shelbi. In Austria, the synthesis of phianite is based on the Russian technology; this product is merchandized under the trade name zirconite, or zirconia. At the market it is usually called cubic zirconia or it is marked with abbreviations CZ, KSZ. Recent years, the industrial production of phianite is organized in China and on Taiwan.

Synonyms. CZ |Diamone -Z | Diamonique | Disconia | KSZ, Germ. and many others | Phainit, Amer.

Search