Abstract: According to the principle of colorimetry, the colour parameter indexes of jadeite jade are quantitized by the gemstone colour auto-measurement system, including 1931CIE chromaticity coordinates, dominant wavelength, chroma, lighness, reflection curves and 1931CIE chromaticity diagram. Through the dominant wavelength, the main tone of the colour of jadeite jade can be distinguished. According to the chromaticity value, the thick degree of green tone can be judged, and the quantitative concept of the fancy green jadeite jade can be defined. By the contrast of the correlation parameters, the negative influence of the black tone to the colour of jadeite jade can be also judged. The results of the experiment illustrate that the gemstone colour auto-measurement system is feasible to the colour evaluation and quantitative description of jadeite jade objectively with the fiber-optic spectrometer, the appropriate method of lighting and spectrum collection and the application of colorimetry principle.