Comparative Study On Heat Treated Yellow To Blue Sapphire And Beryllium Diffused Sapphire From Shandong

In this paper,nine orange-red and yellow to blue sapphires from Shandong were suspected of being beryllium-diffused.In order to confirm whether they were subjected to beryllium diffusion treatment,we compared them with heat-treated yellow to blue Shandong sapphires and one beryllium diffused orange-red sapphire.The sample was subjected to conventional gemological testing,microscopic magnification observation,Infrared Spectroscopy（FTIR）,Ultraviolet-visible absorption Spectroscopy（UV-vis）,Raman Spectroscopy,Energy Dispersive X-ray Fluorescence Spectroscopy（EDXRF）,Laser Induced Breakdown Spectroscopy.（LIBS）and Laser Ablation Plasma Mass Spectrometer（LA-ICP-MS）test.The samples’color are orange-red,yellow to blue.The refractive index is Ne=1.763 to 1.770,No=1.771-1.777,DR=0.008,and one-axis crystal negative light.Transparency is transparent to translucent,bright glass luster.The blue and green blue samples show strong dichroism in blue/yellow-green.The absorption band of 450 nm can be observed under the hand-held spectroscope,and the double-line absorption of the red zone of Cr can be seen in the samples with orange tone.Observed the samples under polarized light that we can see a monoaxial interferogram or a"four bright and four dark"phenomenon,and the sample with the polycrystalline double crystal grain showed partial full brightness.All samples were fluorescently inert.The high-temperature inclusions in the samples are characterized by high-indicative evidence of beryllium diffusion,which is characterized by crystal blushing,poor self-formation（usually containing bubbles）,and surrounding cracks filled with irregular fluids or chunks;the crystallized corundum crystallites filled the healing cracks;the long needle-like inclusions melt and recrystallize to form oriented short needle-like inclusions.Conversely,if the crystal inclusions inside the samples are not damaged,the possibility of being diffusion treatment can be eliminated.The beryllium-diffused samples were immersed in water and magnified to observe the color gamut distribution characteristics associated with the gemstone profile.This is diagnostic evidence that the gemstone has been artificially colored.The specific performance is:the yellow,orange or colorless gamut around the outline of the gemstone wraps the inner natural color gamut,or the yellow to orange or the superimposed color with the natural color gamut covers the entire gemstone,the natural ribbon is covered,and the whole color distribution is presented the middle is deep and the edge is shallow.Except for the two blue samples,the remaining samples were missing the 3310cm^-1 absorption peak associated with hydrogen.Raman spectroscopy indicate that the sapphires in Shandong contains magnetite inclusions.The use of LIBS allows rapid detection of Be elements in some of the beryllium diffusion samples.The Ultraviolet-visible Absorption Spectrum did not find an additional absorption peak of beryllium because the action of beryllium ions in corundum is similar to that of Mg:it is compensated by oxygen vacancies in a reducing atmosphere,and no color is produced;holes are trapped in an oxidizing atmosphere,resulting in intense yellow to orange.Therefore,the diffusion treatment is generally carried out under an oxidizing atmosphere.