Comparison of Internationally Popular Grading & Appraisal Systems of Coloured Gemstones and Its Clues for Setting up a New System

There are varieties of coloured gemstones and each of them has the different influence factors on the quality,and each country or district or nationality has its own special favor for the colour of the gemstones,so it is very difficult to set up a universal quality grading & appraisal system for all coloured gemstones.The ideas and approaches for grading the colour,clarity and cutting of the coloured gemstones are compared and discussed in some international grading systems popularized in the leading countries of the coloured gemstones,such as America,Thailand,Hong Kong and Mainland of China,etc.The results show that the discussed grading systems emphasizing the different influence factors in colour description have the different guiding ideas in the clarity grading,and have the obviously different guiding ideas and approaches in cutting grading for the coloured gemstones,so it is not realistic to set up a universal quality grading system for all coloured gemstones in short time.It is proposed that a two-level scheme of the quality grading system should be tried to set up,that means firstly considering of the clarity and transparency and then integration of the colour,quality and cutting of the gemstones.