Thailand has long been famous for its gems, as it is an important source for many types of gems, such as, the ruby, corundum, topaz, zircon, garnet, and mother of pearl. Thus the Thai gem and adornment industry has received praise both in terms of quality and price from all over. Indeed, gems and adornment are a major Thai export, and is expected to even increase each year.
The beautiful colors of gems have many causes, such as the type of mineral, the compound and atomic structure of the elements present in the crystal, with some of the elements present in very small quantity rendering them very difficult to detect.
The x-ray absorption spectroscopy technique employed by SLRI’s 8th beam line is especially efficient for atomic and compound analysis that are of very low quantity in nature, even able to measure atomic bond distances and determine oxidation states of atoms of interest. Thus it is possible to find the elemental and compound components that affect the color and beauty of each type of gem.
Moreover, the gem industry today is always searching for methods to improve the quality of the gem such as more regular diffusion of color, more glitter and subsequently, more beauty. Some existing methods consist of heat treatment, color diffusion, irradiation, dyeing, foil back, and gem cutting. Each method has its own effect towards the beauty of gems.
Besides employing synchrotron light to study components for better understanding of the beauty of the gem, x-ray absorption spectroscopy has a major role in studying the changes in the atomic structure wrought by these methods, as to approach the ideal process for improving the quality of the gems for even more beauty and acceptability.
SLRI has been continually working with the Thai gem industry to increase value of gems. There has been collaboration between the 8th Beamline researchers and Kasetsart University in studying the color changing process of the sapphire; factors affecting color in the topaz; searching for elements that are integral to the mechanism of changing color of the black pearl, for example. X-ray absorption spectroscopy used in studying the mother of pearl has led to research innovations such as producing gold pearls via synchrotron light, a culmination of SLRI research, including engraving the pearl using synchrotron light, which besides fulfilling value addition for the gem industry in the short term, also provides a knowledge base for the improvement of the quality of Thai gems for even more appreciation.