Abstract
There are some treatments for valuable color of blue sapphire such as dyeing, heating, diffusion. Among of them, heat treatment with development of techniques and effort has been performed for deriving beautiful blue color of sapphire until nowadays. This tendency is caused by recognition that corundum is commonly heated as enhancement.
Improvement of the blue color by heating starts from the 19th century, it was started in earnest in the 20th century[1]. It needed oxidizing-reducing conditions by gas diffusion. The process modifies color of too dark or pale blue sapphire or removes unnecessary inclusions for clarity enhancement[2]. In addition, it needs proper treatment technique which is suited for different geographic origin due to color, impurities, inclusions, etc. Therefore, it is required to various conditions and skills with experience of heat treatment for valuable color of sapphire.
Many Koreans have a lot of interesting in treatment techniques of gemstone for creating added value. One of Korea company has tried to enhance color of blue sapphire by applying with HPHT(high pressure and high temperature) apparatus. The apparatus was designed for synthetic diamond by Russia. It took many attempts with thousands of conditions to finally get to valuable blue color from pale blue color. The president of the company explained that we did not only supplementation of the HPHT apparatus but developed mold was designated for sapphire treatment.
We need to get more information about treatment process and conditions in detail. It is difficult to distinguish the new treated sapphire from general heated sapphire by magnification inspection. But it was observed distinct feature with infrared spectroscopic analysis.
It is noticeable news that valuable blue colored sapphire can be produced by unique process in Korea. Therefore, we need to study to get more information of the newly treated sapphire by HPHT apparatus.
1. T. Ted, The heat treatment of ruby and sapphire, Gemlab Inc., USA (1992) p.xi-xvi.
2. K. Nassau, Gemstone enhancement: History, Science and State of the Art-2Rev.ed, Butterworth Heinemann (1994) p.122-131.
3. T. Ted, The heat treatment of ruby and sapphire, Gemlab Inc., USA (1992) p.141-218.
