According to the relevant provisions of "People's Republic of China (PRC) Product Quality Law", those who engage in social testing and inspection of products in China must pass the re-examination by the national or provincial metrological certification management department and be established or authorized according to law before they can engage in testing and inspection activities. 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 an inspection mark recognized by the national quality inspection, and those who have this mark are qualified to make arbitration inspection conclusions. Having CMA mainly means that the testing personnel, testing instruments, testing basis and methods are all qualified, while having CAL mark is based on the qualification of metrological certification, that is, having CMA, and then the conditions of quality management also meet the requirements. Therefore, it can be considered that having CAL is better than having CMA only in terms of work quality and reliability. The symbol of the national laboratory. This mark indicates that the inspection has passed the examination of China National Laboratory Accreditation Committee, and the inspection ability has reached the level of the national laboratory (CMA and CAL only refer to the approval of provincial quality and technology management). 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. At present, due to the increasingly mature market competition and consumer psychology, in response to the increasingly sophisticated means of counterfeiting in the jewelry industry, testing and inspection must constantly improve their technical level, testing ability and management means, so many testing and inspection 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, there are three symbols of CMA, CAL and CNAL for jewelry detection. At present, there are National Jewelry Quality Supervision and Inspection Center, China Wuhan Jewelry Testing Center and Shanghai Central Laboratory Gemstone Testing Center of the Ministry of Geology and Mineral Resources.