Infrared spectroscopy is a powerful tool for gem identification and research. Therefore, this study was focused to a method of the identification of amethyst, citrine, rock quartz and jadeite by the FT-IR. The FT-IR measurement was very effective in judgement of amethyst, citrine and rock quartz whether they are natural and synthetic. And FT-IR was very useful for the distinguishment of the natural jadeite (A-Jade) from wax/polymer-impregnated jadeite (B-Jade). Such technique will be helpful to identify new challenges present by treatments and synthetics.