Laser Tomography: A New Powerful Method to Identify Natural, Synthetic and Treated Stones. - Case Study of Corundum

摘要

Recently, it becomes very important to observe crystal defects for identifi-cation of gemstones. X-ray topography, X-ray diffraction and so on have been known as methods to detect crystal defect, but damage by X-ray irradiation is a problem for gemstones.However, laser tomography is a powerful method fitting for crystal defects in gem-stones under low magnification and without damage. Moriya and Ogawa (1983) developed this equipment and it is a method to take the tomograph of a transparent object by scanning a narrow laser beam into the sample. It is able to obtain not only a scattering image but also a fluorescence image. We are able to obtain information of crystal defects, such as distribution of impurities, growth sector, dislocation and so on, from images on the laser tomograph. The author describes various features that were observed in natural, synthetic and treated corundum with laser tomography.