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LiuLab Computer Color Grading System

LiuLab Computer Color Grading System (US Patent 7,388,656). 

Our patented LiuLab system is a computer color grading system implementing the Universal Color Grading System for accurate color grading of gemstones and colored diamonds. The LiuLab system generates a reference color to match the average color of a gemstone under the standard viewing environment, and assigns a color grade to specify the color of the gemstone graded. The reference color can be continuously changed by adjusting the hue, lightness and saturation values. The color grade comprises a color name and a corresponding color coordinates. The color name is used for verbal description of the color, and the color coordinate is for accurate color communication in the jewelry industry.

The Universal Color Grading System has been developed for accurate color grading of gemstones and colored diamonds in the uniform CIELAB color space with 22 hue names, 7 lightness levels and 4 saturation intensities. The color names are approximately uniformly distributed in the CIELAB color space. The significant advantage of this Universal Color Grading System is that the true color of gemstones can be accurately graded at the fineness of level 6, and not roughly estimated by other color grading systems and methods.

The color of the LiuLab system is precisely profiled and can be calibrated by users. Therefore, the reference color is always accurate. As an additional benefit to the gem trade, the LiuLab system can be used for accurate color communication among the jewelers and gem trade laboratories at difference places to see exactly the same true color of a gemstone by inputting the color coordinate. If a ruby is graded as Vivid Red (80.00, 56.00, 26.80) by a jeweler or a gem laboratory, for example, the color grade can be sent to jewelers anywhere in the world. The jewelers receiving the color grade can simply input the color coordinate (80.00, 56.00, 26.80) into the LiuLab system and see the exactly the same color of the ruby. Jewelers do not need to guess the color of a gemstone from a color grade obtained by other color grading systems.


            Color space:                                        CIELAB

            Color display (Reference color)             Continuous in the CIELAB color space

            Color display resolution:                     <0.1 DE (CIELAB)

            Color Names:                                      Universal Color Grading System         


            Visual color comparison between the reference color and the average color of a gemstone. A color name associated with the Universal Color Grading System and the color coordinate are simultaneously displayed for the reference color.


System Components:

Computer:  Window XP or later, 1 GHz CPU, Hard Drive 120 GB, Memory 1.0 GB, CD driver.

Monitor:     14" or larger CRT (Profiled and Calibrated)

Software:   LiuLabGemColor Version 6.0.0 or later




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Last modified: 01/22/15.