Abstract: Turquoise occupies an important position in the jewelry market. Due to its uneven in quality, there are a lot of treated turquoises in the market. This paper mainly studies filled turquoise in detail. The gemmological characteristics and infrared spectra of the turquoise samples before and after filling were obtained and comparatively analyzed by observation, density measurement and infrared spectrometer.After filling treatment, the porosity, hygroscopicity and density of the turquoise samples changed. Vibration frequencies of CH₂, CH₃, C=O and C-O-C groups appeared in infrared spectra.Infrared spectrum and PYGC-MS were used to determine the structure and composition of the filling solution, which are ethyl polysilicate, triethylene glycol dimethacrylate, ethylene dimethacrylate with benzene ring substitution, mixture of cyclic olefin resin and cyclic aliphatic anhydride curing agent, aluminum dihydrogen phosphate doped with Cr₂O₃ or chromium phosphate binder, aluminium dihydrogen phosphate doped with copper salt.