jadeite, fei cui, b-jade, gems, gem treatments, bleached jade, impregnated jade

X-ray photoelectron spectroscopy (XPS) is investigated as a non-destructive method for identifying wax and polymer in bleached and impregnated fei cui and as a complement to infrared absorption spectroscopy. Sixteen specimens from Myanmar were examined, comprising four rough specimens, five naturally coloured polished specimens and seven bleached, wax- or polymer-impregnated polished cabochons. Preliminary testing included refractive index, immersion in di-iodomethane, visible absorption spectroscopy, ultraviolet fluorescence and Fourier-transform infrared spectroscopy. Refractive indices, immersion behaviour and visible absorption features did not reliably distinguish treated from untreated material; ultraviolet fluorescence provided indications of treatment in some specimens but was absent in others. Infrared spectra differentiated weak wax absorptions associated with conventional polishing from the much stronger absorptions of wax-impregnated specimens, while multiple strong bands between 2800 and 3100 cm⁻¹ identified polymer impregnation. XPS measurements, made after cleaning the surfaces with propanol, determined surface elemental composition and carbon bonding characteristics through survey scans and high-resolution carbon spectra. Untreated, unwaxed specimens showed the principal elements expected for jadeite, together with minor surface carbon and calcium. Their carbon-to-sodium signal ratio was approximately 2.5, compared with approximately 12 for wax-polished specimens, 11 for wax-impregnated specimens and 35 for polymer-impregnated specimens. The substantially greater carbon signal in the polymer-treated group distinguished it from the wax-bearing groups. Analysis of the carbon peak components provided further discrimination: wax-bearing material showed aliphatic, ether and ester contributions, whereas the polymer-impregnated specimens showed aliphatic, aromatic or phenyl, carbonyl and ester contributions. Ether carbon was characteristic of the wax examined, while phenyl and carbonyl components characterised the polymer used in these specimens. A significant limitation is that XPS samples only the outermost surface, to a depth of approximately 5 nm, and therefore could not distinguish conventional wax polishing from wax impregnation on the basis of their similar surface compositions. Infrared absorption measurements remained necessary to assess the greater bulk wax content associated with impregnation. The study demonstrates the complementary roles of surface-sensitive XPS and bulk-sensitive infrared spectroscopy: XPS identifies surface fillers and their chemical characteristics, while infrared spectroscopy helps establish their abundance within the material. Together, the methods provide stronger evidence for identifying treated fei cui than routine gemmological observations alone.