Host: The Gemmological Society of Japan
Pages 21
A Korean company developed a new enhancement method of changing color of blue sapphire using an apparatus to produce synthetic diamond which is modified for mold press machine. They use the temperature of the treatment is to be in the range of not much higher than synthetic diamond product processing and applied low mechanical pressure.
In this study, we conducted an experiment with pressure and temperature variable in order to analyze the gemological and spectroscopic properties of before and after enhanced sapphire. Changes of some inclusions and UV-Vis spectra observed after the enhancement are similar to these changes found in conventional heated corundum. However, a strong absorption band related to a structural OH group that did not exist in the infrared region of all samples was formed.
Conclusive identification of these treated sapphires requires infrared spectroscopy and sometimes accompanied by some indication of standard heat treatment. Moreover, some fissures and fractures developed from their internal inclusions such as crystal and negative crystal. In addition, a definite color band and zoning usually became less prominent after enhanced by this method.
For this study, also, we examined more than 20 sapphires, rough and polished. All of the samples were experimented with their general appearance, basic gemological properties, microscopic features, trace element chemistry, visible and infrared spectroscopy. We have described the properties of before and after new enhancement of blue sapphire in this study.
