Gemological Institute of America (GIA) has developed a diamond color measurement instrument that can provide
accurate and reproducible color measurement results. The instrument uses uniform illumination by a daylight-approximating
light source; observations from a high-resolution color-camera with nearly zero-distortion bi-telecentric
lens, and image processing to calculate color parameters of diamonds. Experiments show the instrument can provide
reproducible color measurement results and also identify subtle color differences in diamonds with high sensitivity. The
experimental setup of the prototype instrument and the image processing method for calculating diamond color
parameters are presented in this report.