Study on the Treatment Turquoise Using Raman Spectroscopy

Due to a variety of the enhancement and treatment turquoises discovered in gem markets, the identification of turquoise is becoming more and more difficult. By using laser Raman spectroscopy analysis, the characteristics of Raman spectra of the pressed and filled turquoises were studied. The results show that laser Raman spectroscopy is an effective technique to identify the enhancement and treatment turquoises and the natural ones, moreover, it's a non-destructive testing method. The Raman spectra of the enhancement and treatment turquoises are resulted mainly from the vibrational mode and frequency of water, hydroxyl units, PO(4) tetrahedron and CH(2) units. Besides, they have the characteristic Raman spectra peaks at 2 937, 2 883 and 1 451 cm(-1) which are attributed to the stretching vibration and the bending vibration of CH(2), respectively. These characteristic Raman vibration bands, it will help to distinguish the natural turquoises and the treatment ones. The study provides a new train of thought on the rapid, accurate, and non-destructive identification of turquoise.