| 146 turquoise samples ranging from sky blue, green, to yellow selected, a comprehensive study was given to these samples from Zhushan, Hubei Province regarding their color mechanism and quantitative characterization. It indicates that red samples contain relatively more Mn2+(0.041%). With the use of EPMA line scanning, chemical element analysis (to obtain the ion content of Fe2+, Fe3+) and Colorimeters (with CIELAB Uniform Chromaticity Model), it is discovered that the high content of Mn2+and the low content of Cu2+together lead to the red color, and that the color of sky blue (b* from -4.78 to -9.64) in turquoise is decided by Cu2+ (from 6.175 to 6.696 in the chosen samples), while green(a* from -19.13 to -34.50) by Fe2+ (from 0.23 to 0.54 in the chosen samples) and yellow(b* from 4.55 to 11.27) by Fe3+(from 3.36 to 3.83 in the chosen samples). The lightness is affected by Fe2+, Fe3+ and Cu2+ in positive correlation with Fe3+ and negative with Fe2+ and Cu2+. Besides the coloring ions, the mineral water has impact on the color of turquoise. The Hue Angles of the five samples are ranging from 172°to 194°, and the Saturation is from 13°to 31°. The Saturation of the most brilliant turquoises in the market is more than 30. At last, the quality evaluation system is provided comprehensively with consideration of other factors, such as iron line, texture and cut. The aim of the paper is to find out the inside-water impact on turquoise. Water sorption measurement is to leave the samples in water within same amount of time and use the Colorimeters to measure the Color Scale Data at each stage. With the increase of the absorbed water, the Hue, Saturation and the Lightness are changed especially in 1.5 hours. Within 36 hours, the Color Difference(CIE 2000 Difference Formulas ) of blue group is between 4.20～7.26, while green group is between 1.28～5.49. In dewatering measurement one sample is divided into two pieces: one is made to do the Different Thermal Analysis, and the other is made into slice (1cm diameter, 2mm thickness). Through the Different Thermal Analysis we can get the temperature of dewatering of the Absorption Water, the Crystal Water and the Structural Water, 150℃, 350℃and 530℃respectively. The total water loss is 17.78%～19.57%. Crystal Water is the highest, about 10%, Absorption water 5% and Structural water4%. After heat-treatment for the slice, the Color Scale Data is measured. It is discovered that the most important effect of the dewatering of Absorption Water is the hue of the green color(a* from -12.06 to -4.57)and the Saturation(C* from 17.55 to 12.32). When Structural Water is deprived, the turquoise is destructed and becomes yellowish gray color powder. To observe the difference of appearance and microscopic structure before and after the lost of inside-water, we use SEM to observe the turquoise deprived of Absorption Water and some Crystal Water (230℃). It's found that the crystal particles becomes bigger and profile clearer. The hand sample becomes greenish gray and waxy luster is turned into earthy luster. When Structural Water is deprived(700℃), and the border of the crystal becomes round. The samples selected have same character of the Infrared Absorption Spectroscopy, including position and strength of the absorption band. The Infrared Absorption Spectroscopy shows that 2926cm-1 absorption peak appears when Absorption Water and some of Crystal Water(230℃) are lost; 2924 and 1853cm-1 absorption peak appears, PO43- stretches and bend vibration are damaged when Structural Water absorbed. The samples selected have basically same Raman Spectroscopy in vibration frequency and strength. With the temperature increasing from 200℃to 1480℃, there is only left 250cm-1 vibration peak. If the temperature continues to increase, Raman Spectroscopy cannot distinguish.
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