Fig. 5
From: Unraveling the luminescence secrets of turquoise nucleus cultivated pearls
(a) FTIR spectra of the nuclei of TNC pearl samples (IT1, IT2), and gibbsite (G1), (b) FTIR spectra of natural turquoise (NT1), filled turquoise (FT1) and compressed carbonate powder imitation turquoise (CIT1). Spectra are offset vertically for clarity.
