An Analysis of Infrared Spectra of Red-yellow Jadeites by Heat Treatment

The value of red-yellow jadeites is very different depending on whether they have been processed with heat treatment, With an increasing demand for red-yellow jadeites, it has been a key as well as difficult issue to distinguish whether the jadeites are experienced heat treatments or not. In this paper, the heat treatment experiments are carried out on the red-yellow jadeites, and the infrared spectra of the jadeites before and after heat treatment are also compared, The results show that different spectral characteristics, i. e, the variation of intensity for four absorption peaks due to the hydroxyl structure of jadeite: (1) obvious changes appear at 3 000-4 000 cm^-1 from U structure before heat treatment to V structure after heat treatment; (2) small changes appear at 3 622- 3 628 cm^-1 or 3 670 cm^-1.These features could be used as the assistant diagnostic index to determine whether the jadeites have been heat treated or not.