According to the relevant provisions of "People's Republic of China (PRC) Product Quality Law", the institutions engaged in social testing and inspection of products in China must be qualified by the national or provincial metrological certification management department in conjunction with the recognized institutions, and can only engage in testing and inspection activities after being established or authorized according to law. The contents of metrological certification assessment mainly include the qualification (level) of personnel, the accuracy and precision of inspection equipment and instruments, whether there are necessary workplaces and conditions, whether there are sound work, management rules and regulations, whether there are correct working basis and inspection methods, and so on. CAL- is the symbol of inspection organization approved by national quality inspection, and the organization with this symbol is qualified to make arbitration inspection conclusion. Having CMA mainly means that the testing personnel, testing instruments, testing basis and methods are qualified, and the premise of having CAL mark is that the measurement certification is qualified, that is, having CMA qualification, and then the quality management conditions of the organization also meet the requirements. Therefore, it can be considered that CAL is better than CMA only, and the working quality and reliability are further improved. The symbol of the national laboratory. This mark indicates that the inspection institution has passed the examination of China National Laboratory Accreditation Committee, and its inspection ability has reached the level of national laboratories (CMA and CAL only refer to the approval of provincial quality and technology management institutions). According to the relevant agreements of China's accession to the WTO, the "CNAL" symbol can be recognized internationally, for example, by the United States, Japan, France, Germany, Britain and other countries. Any of the above three marks is valid, especially the first mark CMA, which is the basic requirement of national laws for testing and inspection institutions. At present, due to the increasingly mature market competition and consumer psychology, and in order to cope with the increasingly sophisticated means of counterfeiting in the jewelry industry, testing and inspection institutions must constantly improve their technical level, testing ability and management means, so many testing and inspection institutions have the above three signs at the same time, and have the ability and level required by the three signs. It can be understood that with the identification certificate of the above three marks, there are "three risks". At the same time, it has three jewelry testing institutions: CMA, CAL and CNAL. At present, there are National Jewelry Quality Supervision and Inspection Center, Wuhan Jewelry Inspection Center and Shanghai Central Laboratory Gem Inspection Center of the Ministry of Geology and Mineral Resources in China.