Ключевое слово: «blue sapphire»

. In this study, the internal features of ten round cut sapphire gemstones with weight 0,06 to 0,96 carats and diameter 2,49 to 6,11 millimeters were examined using optical microscopy by binocular gemological microscope. A visual examination of the stones showed they did not meet the typical quality of standards for round diamond cutting. The following types of internal defect clusters were identified: veils, fingerprints, and growth zoning. Based on a number of detected features, it was determined that the samples were natural in origin and were treated by heating to improve the coloration of sapphire samples. This work confirms that the analysis of inclusions is an important part of determining the nature of sapphires.