Cubic zirconia is the latest diamond imitation and may be the most convincing substitute yet made. It was first manufactured in Russia under the name of "Phianite". Other major producers are the Djeva Company in Switzerland who markets it under the trade name "Djevalite", the Ceres Corcoration- Waltham Massechusetts, and ICT Inc.- Shelby Michigan. One distributor in the U.S. markets it under the name, "Diamonesque".
Gem quality crystals of cubic zirconia are grown by the "skull melting" technique developed in Russia. Unlike other melting techniques this method uses a "cold crucible" or "skull" to hold the melt of ZrO2 plus a stabilizer within a crust of its own powder. The material Within the "skull" is heated and melted by high energy radio frequency waves which pass through the "skull" similar to the melting and heating of an ice cube in a paper cup in a microwave oven.
The properties of cubic Zirconia (ZrO2) are: refractive index 2.15 to 2.18, specific gravity about 6, dispersion 0.060 to 0.063, and hardness
7-1/2 to 8-1/2. The variation in properties is caused by the difference
in the chemical composition and the amount of the stabilizer used by
the different manufacturers. Most cubic Zirconia fluoresces a yellowish
orange under long-wave and a yellow color
under short-wave ultraviolet. Some stones do not fluoresce under
long-wave ultraviolet.
