GemResearch Swisslab (GRS) Specializing in Origin Determination of Fine Rubies and Sapphires

Origin of Color Analysis of Natural Unheated "Padparadscha" - Sapphires from Madagascar


Fig. 24 Representative absorption spectra of natural brownish orangy-pink sapphires from Madagascar unenhanced by heat. Some of the samples are reminiscent of "Padparadscha" colors. The interpretation of origin of color, indicated for chromium (Cr³⁺, band centered at 405-410nm and 550 to 560nm, sharp lines at 475, 477 and 693nm), iron (Fe³⁺, line at 388nm and Fe³⁺- pairs, line at 450nm and at 377nm) as well as color centers, based on chemical compositions determined by ED-XRF (Fig. 23), LA-ICP-MS analysis and literature (Lit. 04 and 28). Representative LA-ICP-MS analysis: Mg= 91ppm, Ti= 89ppm, V=21ppm, Cr=521ppm, Fe= 4937ppm, Ga= 101ppm, no Beryllium (Average 17 analysis, sample No GRS 12737, LA-ICP-MS, sample No. 12737, Table 6, Part B).

Fig. 25 Iron (Fe), chromium (Cr) and titanium (Ti) concentrations (ED-XRF analysis in oxide wt.-%, See tab. 5) of fancy natural sapphires unheated (blue), and enhanced with the new E(IM1) method (red). Note: Enhanced sapphires E(IM1) are not enriched in these trace elements (Fe, Cr and Ti) in comparison to those unheated (N).