Gemmological Characteristics Of Rough Diamond From Australia

In the present thesis we focus exclusively on natural rough diamonds of Australia.The samples are studied using many simple gemological tools and expensive instruments(e.g., Fourier Transform Infrared Spectroscopy, Polarizing Microscope,DiamondView,Photo-luminescence, UV-Visible Absorption, and so on.) to give systematic research on strong indications of diamond characteristic features, such as their surface crystal micro-morphology, their spectroscopy feature, their internal textures, their colors, and the types of inclusion their contain.The crystal morphology of 6 diamonds in Australia are octahedral, rounded dodecahedron and some diamonds are classified as irregular which they do not exhibit an identifiable crystal shape. Their surface crystal micro-morphology included Hillocks, shield-shaped laminae, imbricated shield-shaped laminae on the surface and so on, the main relative factors of the crystal morphology of samples were resorption and plastic deformation, which indicates that they suffer form strong resorption and plastic deformation during the formation of diamonds in Australia.The FTIR spectrums can be identified their diamonds type are IaAB and impurities are nitrogen and hydrogen. There are three types classification of 6 diamonds in Australia according to the presence or absence of nitrogen, diamonds contain aggregated N impurities-including A-aggregates(IaA), which consist of pairs of N atoms, and B-aggregates(IaB), which are made up of four N atoms around a vacancy (V), and nitrogen platelet. Those peaks at 1010 cm-1,1330 cm-1,1428 cm-1 have relation to slip plane (111) and the plastic deformation during growth of diamond's crystal were confirmed.Each type show distinctive fluorescencecolors and patterns of samples when examined with the DTC DiamondView and Polarizing Microscope showed that they were grow up not the same stage. They are suffer form resorption and plastic deformation in different degree during growth process. The difference of internal growth characteristics in samples indicated that the formation of Australia diamonds is not same geological environment and stage.The 6 Australian samples with transparent uneven brown body colors, test Results of Photo-luminescence and UV-Visible Absorption displayed the peak at 503nm, 496nm, 415nm, 613nm and 576nm, their uneven brown body colors caused by the interaction of those peaks. As far as we concerned that the peak at 576nm is caused by plastic deformation and is believed to result in the brown color.