1.Gilder certificate is a jewelry appraisal certificate issued by GUILD Gemological Laboratory in the United States. Founded by American gemologist MrCharlesCarmona. The types of inspection reports that can be issued include advanced reports and routine inspection reports. It is suitable for all gemstone varieties and meets the requirements of various gemstone detection in the market.

2.ltc is an important institution jointly established by UNCTAD and WTO to promote technical cooperation and trade between United Nations agencies and developing countries.