IDENTIFICATION OF B JADE BY FTIR SPECTROMETER WITH NEAR-IR FIBRE-OPTIC PROBE ACCESSORY

A FTIR spectrometer with a near-IR fibre-optic probe accessory has been found to be a useful and non-destructive tool for identification of bleached and polymer-impregnated jadeites (so-called B jade).
This method has the advantage of application to the testing of not only very thick or mounted stones, but also very large samples such as bracelets, which are difficult to test with other IR techniques. The important features of the technique are use of the fibre-optic probe and measurement of the near-IR frequency range. Therefore, clear near-IR absorption spectra from 7400 to 4000 cm^-1 could be obtained. The absorptions are caused mainly by the combination of stretching and bending vibrations and the harmonics of stretching vibration of C—H bonds.