Identification Methods of Sri Lankan Corundum in Comparison to Other Common Gemstones

Abstract: Sri Lanka is one of the leading countries in export of high quality corundum (Al2O3) gemstones due to the Precambrian rocks geological background. Combined highgrade metamorphic silicates and carbonate rocks makes perfect conditions for crystallization of this mineral. Weathered and eroded rocks have been transported by fluvial processes and formed gem gravels that are located throughout the country but mainly in the Highland complex of Sri Lanka. In order to determine whether a gemstone is corundum or any other gem mineral different techniques and instrumental methods are used. This report focuses on instrumental methods used to measure the minerals physical properties in order to get a definite mineral identification. Mineral identification in gemological circles is critical for determining the commercial value of a specimen. Factors like transparency and color of and inclusions in gemstone have to be taken into account when evaluating the value of a specimen. It also needs to be distinguished from artificial gemstones and heattreated specimens that in recent years have become more common due to more advanced techniques. By examine inclusions and the chemical composition of a rough or facetted specimen the origin and process can be determined.