CHROMATIC RESEARCH OF GREEN JADEITE JADE

Jadeite is a very famous Jade, in order to solve some problems on certification and synthesis, to understand its color, some chromatic problems of metamorism and color difference in chromaticity were studied. Both iron and chromium ions can cause the green color of jadeite. The color of sample with relatively high Cr3+ is mainly determined by the spin-allowed transitions of Cr3+ ions in the visible region, while the color of sample with relatively high Fe is due to the charge ¨Ctransfer transitions, that is Fe2+ (M1) °ú Fe3+ (M1). These two theories is the real reason of metamorism of different jadeite jade. A calculation procedure was programmed using VB language according to chromatic theory. On the basis of absorption spectra data, the CIE (Commission International de I'Eclairage) chromatic coordinates; the tristimulus values, visual reflectance, dominant wavelength and saturation were calculated. Color difference of different kinds of jadeite jades were calculated by color difference program. Because the properties of metamorism was broken by different illuminants, on the basis of CIE 1931 standard colorimetric oserver, the degree of metamorism was be evaluated by metamorism program. The effects of view angle and standard illuminators on calculation results were discussed. And dicussed the determinants of jadeite jade°¯s transmittance. It is indicated that the purity of mineral components, the density of structure and the quantity of microfissures, fillings in microfissures on the surface of jade and its microcaves on the surface of jade could worse its transparency, and in the reverse.