Automatic grading measurement method of diamond color

Abstract

The invention discloses an automatic grading measurement method of diamond color; the method includes steps of adjusting lighting and observing conditions so that the testing environment is consistent with environment observed by human eye; accurately positioning by a microscope zone so that the tested point is completely consistent with the measurement position point of a standard colorimetric stone when diamonds with different grains are measured; collecting an image signal and a spectral signal of a sample waist part and a pavilion and every position closing to the bottom point; contrasting a color coordinate of the measurement sample with the color coordinate of every grade standard colorimetric stone point by point; calculating the differential value between the color coordinate of the measurement sample and the color coordinate of every grade standard colorimetric stone, making the color grade of the measurement sample close to the national standard grade with the minimum differential value of the chromaticity coordinate; if the differential value of the color coordinate is consistent with two grades of standards, closing to the lower grade standard. The method guarantees the consistence of the diamond color grading and human eye observation by the automatic measurement system, simulates the traditional colorimetric environment of human eyes, and reduces the bias of the measurement system caused by different observing conditions.

Description

technical field [0001] The invention relates to a measuring device and method conforming to visual diamond color grading, in particular to an automatic measuring method for diamond color grading. Background technique [0002] Diamond color is a very important indicator in diamond evaluation. The national standard is divided into 12 continuous color grades according to the change of diamond color, which are represented by letters and numbers: as shown in Table 1, [0003] Table 1 Diamond Color Grade Table [0004] D 100 E 99 F 98 G 97 H 96 I 95 J 94 K 93 L 92 M 91 N 90 <N <90 [0005] The above-mentioned color grades are all calibrated by master stones. A set of standard color stones is essential in color grading. Our country uses a set of 11 standard color stones. Diamond color grading has always been carried out mainly by human eye observation. This human eye observation method is very strict...

AI Technical Summary

Problems solved by technology

Therefore, there are differences between the detection results of this method and the way of human visual color, resulting in differences in grading results

At the same time, due to the different sizes of the tested diamond samples and the difference in the optical path of the light passing through the sample, the repeatability and reproducibility of this method cannot meet the requirements of the measurement results.

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