Gemmological Characteristics And Heat Treatment Of Amber From Burma

As one of the world’s oldest gemstones,the price of Burma amber soared in recent years, which has become a hotspot of research. In this paper, The characteristics of Burma amber are studied by using the gemological instruments, Polarizing microscope, Infrared spectrometer, Raman spectrometer, Ultraviolet-visible spectrophotometer and X-ray powder diffraction(XRD) spectrometer. In addition, the author compares the changes before and after the heat-treatment experiments of Burma amber.By using conventional gemological methods, we know that the specific gravity of Burmese amber is 1.04 to 1.06 and its mohs hardness is 2.03 to 2.10. The amber samples show a strong and uneven blue-white fluorescence, which also shows abnormal interference colors. In the functional groups and the aliphatic structure of Burma amber we get that the absorption peaks of carbonyl C=O stretching vibration are slightly different. The Baltic amber’s higher peak in 1736 cm-1 can be distinguished with Burma amber’s in the range of 1724~1732 cm-1, while Mexican amber’s absorption peak in 1705 cm-1 is lower than Burma amber’s peak. The "Baltic peak" in 1159 cm-1 can differ from Burma amber. Ultraviolet-visible spectrophotometer analysis shows that the peak in the range of 200~215 nm is caused by the Ï€â†'Ï€* transition, and the peak in 250 nm is caused by the nâ†'Ï€* transition.Comparing the characteristics before and after the heat treatment of Burma amber, we get the results. Firstly, the color after heat treatment have connections with the heating temperature and time. Secondly, heat treatment changes the color of UV fluorescence, which becomes weak or disappear after heat treatment. Thirdly, the C-H bonds decrease while the carbonyl C=O, alcohol, ether and ester increase. Several peaks of oxygen-containing functional groups in the range of 976~1227 cm-1 turn into single peak. The oxygen-containing functional groups probably attribute to getting red in the heated amber samples; Finally, the characteristic peaks of Raman spectra are weaker than heated before; Characterless peaks of Ï€â†'Ï€* or nâ†'Ï€* transition are the important evidences for the heat treatment amber.