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Survey of the Chemical Composition of Natural Sapphires of Different Colors Produced by the New E(IM)-Method
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Fig. 33a, b ED-XRF chemical analyses (in oxide wt.-%) of different natural colored sapphires enhanced with the new method. The samples from the first two graphs originate from the same heat treatment run of pastel colored sapphires from Madagascar (See materials f.).The group of colors indicated via No. 2 corresponds to samples which were re-polished after treatment, and which are not from the same heating run or the same heat treatment laboratory. The golden yellow, and lemon and yellow, group (Y) is indicated, as well as the field of orange to orangy-pink colors (P). Note: White sapphires are those that did not change after heat-enhancement with the new E(IM1) method. Compare P (these figures) with Fig. 23. BO and the field designated as Y. It can be noted that the chemical compositions (as determined at the surface of the gemstones by ED-XRF analysis) are much lower than the natural counterparts with the same color (compare Fig. 23 and Fig. 33).
Conclusions on ED-XRF and UV-VIS-NIR
The chemical analysis and spectroscopic study were carried out on fancy sapphires of different colors from Madagascar, both for gemstones unenhanced by heat (N) and, in comparison, for gemstones enhanced by heat with the new E(IM) method (Compare 23, 25, 33a). Comparing the quantitative data, (e.g. focusing on the concentration of trace elements between enhanced E(IM) and unenhanced (N) sapphires of the same color, and the intensity of the absorption lines, Compare Fig. 22a, 24 with 26 and 27), the following major differences were noticed:
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Copyright 2002 © GRS
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