gems, zircon, Cambodia, heat treatment, FTIR

Zircon is a valuable and beautiful gemstone. The favourite colour of zircon in the gem market is blue, which is commonly obtained by heating the reddish brown variety. Heat treatment of zircon is the most conventional method to improve their colour. The famous locality of heated blue zircon is Ratanakiri Province, North Eastern Cambodia. Nowadays, the amount of gem quality rough zircon is decreasing because mining areas are mainly replaced by rubber plantation. Then, zircon samples from another source have been investigated for heat treatment. Kanchanaburi Province, Thailand is an important source of blue sapphire; besides, zircon has also been found in sapphire mining areas. Zircon samples from Kanchanaburi are also reddish brown in colour similar to those of from Ratanakiri, but are smaller in size. The aim of this study is to examine and compare the heat treatment results of zircon samples from Ratanakiri and Kanchanaburi.