Apparatus and method for color measurement and color grading of diamonds, gemstones, and the like

Abstract

The present invention discloses method for color measurement and color grading of faceted gemstones, diamonds and the like. A novel three-step calibration insures an accurate spectral measurement of the sample inside the measurement integrating sphere. Using the method of the present invention, a computer provides measurement parameters calculated from the physical parameters of the measured sample, including, but not limited to, shape, dimensions, refractive index, intensity of fluorescence and cut grade. By means of the present invention, a computer then calculates the spectral reflectance and colorimetric data, and determines an average color grade by checking a look-up-table that represents the relationship between the CIELAB coordinate and the average color grade, and it also determines a true color grade based upon the average color grade and the physical parameters, using mathematical analyses and algorithms.

Dependencies are inferred from the claim text.