Abstract: The inventive method, which provides an accurate, objective and readily reproduceable characterization of the total colored appearance of a gemstone, includes the steps of identifying the main and overlay colors of an illuminated gemstone from among a predetermined set of primary colors by comparison of the stone with a series of reference color charts representing standard samples of the primary colors and of composite mixtures of the primary colors, identifying by comparison the proportion of overlay color to main color in each stone with respect to such proportion in the selected color chart to determine the overlay level, identifying the color saturation of the composite coloration of the gemstone by comparison with the selected color chart to determine the zone of coloration of the stone, and overlaying a color mask and the selected color chart to identify the degree of color masking present in the gemstone.