In this paper, the important role played by an infrared spectrometer in the kind identification of gemmology, the determination of optimal treatment and the distinguishment of natural gems from synthetic gems without prefabrication and abrasion is presented by way of example. By comparison, although the conventional identification of gem species is more easy and quick, it runs a certain risk. However, it is impossible to determine whether the gem is treated optimally and distinguish the natural gem from the synthetic gem by using the KBr pellet. The conventional application of infrared spectra is of practical significance to the discussion of the macroscopic structure of crystal, the interaction of polycrystalline aggregate and the configuration and O-H content in mineral and rock. The infrared spectral characterization of the crystallization of SiO2 gems is given.