Abstract: Turquoise is a mid-class gem.The evaluating of the turquoise's quality given by the gemologists before are always roughly.The evaluating of the turquoise's color also is always given by naked eye.In virtue of Gem Dialogue classification rules on color,the paper graded the 14 turquoise samples according to color,pattern,texture and cut.Compared to the samples' marketing prices,the result of the turquoise samples given by quantitative-analysis is corresponding.The turquoise always appears aggregation,its color,texture,transparence are different from high-class to inferior-class.So,the quantitative-analysis about the turquoise has some limits.