A method of color grading gems by a user by their inherent properties of shape, hue, tone and saturation. Each of the properties is variable over a practical range derived from a database. The database is created by digitally coding gem shapes, hues, tones and colors from digital photographs of gems of different, shapes, hues, tones and saturation. The variable properties are displayed on a screen and the user selects the best matching respective shape, hue, tone and saturation in comparison to the particular gem being graded. Upon receiving the user's selections, an image of the a gem having the shape, hue, tone and saturation selected by the user is displayed on the screen and translated into alpha-numeric code which can be communicated to any other user of the same system, enabling remote discussion and evaluation of the same target gem.