Abstract: The principle and method of the gem identification by scanning electron microscope (SEM) with energy-dispersive X-ray spectrometer (EDS) in the low vacuum mode are introduced.The quantitative data without standard samples of EDS is compared and evaluated with that of the standard document data in the paper.Moreover, some problems in the gem identification by using SEM with EDS are also discussed.Furthermore, compared with the other instruments, such as XRF, XRD, FTIR and LRS, the application of SEM with EDS is one of the best convenient and efficient methods in the gem identification.