Spectroscopy Characterization of Multi-Treated Yellow Sapphire from Changle, China

Be-diffused yellow sapphires from Changle, Shandong Province, are studied by using magnification observation, ultraviolet-visible (UV-Vis) Spectroscopy, infrared (IR) Spectroscopy and Laser Ablation Inductively Couple Plasma Mass Spectrometer (LA-ICP-MS). The high content of Fe, Ti and Ga, is the typical for sapphire from basalt origin from Changle, while the Be concentrations indicate those sapphire are heated with Be Be diffused,. The IR absorption band at 3310 cm-1 of OH vibration disappears, which suggests those sapphires are heated at high temperature in a highly oxidizing atmosphere. The Fe3+ absorption bands in UV-Vis at 377, 380 and 450 nm, confirm the sapphires are heated in oxidizing atmosphere, while Fe2+-related absorption bands at 735 and 847 nm prove those yellow sapphires are from reducing atmosphere after Be-diffusion. The results of IR, UV-Vis and LA-ICP-MS indicate those yellow sapphire are originally from basalt in Changle and treated through multiple procedures, involved of Be-diffusion in highly oxidizing atmosphere and heat in reducing atmosphere. The Be-diffusion treatment diffuses beryllium into the crystal lattice in oxidizing atmosphere to lighten dark blue tones and make yellow color appear. Moreover, the sapphires undergo second heat treatment in reducing atmosphere after Be-diffusion to reduce the brown tunes of diffused sapphires.