The standard "GB/T 17722-1999 sem measurement method for film thickness of gold coverings" specifies the technical requirements for the measurement of film thickness of gold coverings in gold products using sem (SEM) and electronic probe. The method is suitable for gold coverings with a film thickness range of 0.2 to 10 microns, and can also be used for the measurement of Miscellaneous metallic material coverings. The standard describes in detail the sample prepative process, including the steps of adding a metal protective layer, cutting, mosaic, grinding and polishing, and directly measuring the number of layers and the average Film thickness of the coverings by sem observation of secondary electron images and backscattered electron images. The standard also refers to relevant reference documents to ensure measurement accuracy and conformity.