Fig. 1. Samples of turquoises

Fig. 2. Relative density plot of Turquoise samples

Fig. 3. Surface characteristics of turquoisestreated by “Porcelain-Added”
(a, d): Granular transparent crystals and hairy filaments; (b): The change of luster; (c): Local blue spots appear

Fig. 4. UV-Vis absorption spectra of some turquoise samples

Fig. 5. Infrared spectra of natural turquoises

Fig. 6. Infrared spectra of turquoisestreated by “Porcelain-Added”

Fig. 7. Plot of main element content of samples