Many Chinese freshwater and marine pearls are treated by radiation and dye in the pearl market to imitate Tahiti pearls. It is important for gems labs and jewelry business to identify Tahiti pearls, irradiated freshwater cultured pearls, black dyed Chinese freshwater and marine pearls easily and accurately. Raman spectrum was used to observe theses pearls. According to the results, dyed freshwater and marine pearls show special peaks around 1 352 and 1 587 cm^-1 produced by dyeing material like Ag⁺. Tahiti pearls spectrum assumes peaks from 1 259 to 2 532 cm^-1 related to porphyria pigments peaks and conchaolin, while only weak aragonite υ₁ peak around 1 087 cm^-1 and υ₄ peaks around 702～705 cm^-1 exist in irradiated freshwater cultured pearls' spectra.