Infrared spectroscopy is a powerful tool for gem identification and research. Absorptions of a gem material in the infrared region of the electromagnetic spectrum are due to vibrations in the crystal structure; they can be used to help separate one gem material from another or to detect certain types of treatments. The authors describe the new Nicolet 60SX Fourier transform infrared spectrometer recently acquired by Gemological Institute of America's Research Department, and outline the detection of polymer impregnation of opal as an example of the use of infrared spectroscopy in gemology. -- AATA