Key Technology and Interpretation of the Association Standard: Blue Amber Grading

Blue amber refers to a specific kind of amber which has yellow, brown, or yellowish-green body colour under white background, with a different blue hue on the surface when exposed to natural light under black background. This phenomenon is more obvious under ultraviolet light. Due to the rare production, unique colour characteristic, huge quality differences, and the chaos of market, the quality grading of blue amber is imperative. In this paper, key technologies, such as the blue appearance formation mechanism, the selection of quantitative method and evaluation index for characterization were analyzed by using three-dimensional fluorescence spectrometer. And the optimization of grading project, the determination of the grading conditions and the main contents of the association standard, the Blue Amber Grading were unscrambled minutely. The following conclusions were gotten: the blue appearance is fluorescent colour caused by aromatic compound in its own; a three-dimensional fluorescence spectrometer with wide applicability can characterize the fluorescence behaviors of blue amber; strictly controlling the geometric conditions among the light source, the sample and the detector can make the test results more consistent with the luminescence phenomenon observed by naked eyes under D65 light on a black surface; the data, collected by the instrument, according to the relevant national standards, can calculate blue amber fluorescent colour's chromaticity coordinates (x, y) in the CIE 1931 colour space system and the relative intensity of fluorescence can then be found. The main contents of Blue Amber Grading include: terms and definitions, categories of body colour, grades of clarity, grades of fluorescence, etc.