It’s true, FS is usually the manufacturer’s mark. Thousand pure gold means that the gold content is not less than 999, which is the highest value in the naming of jewelry fineness. When jewelry is made from precious metals of different materials or purity, the material and purity should be expressed separately. When jewelry cannot be marked due to reasons such as being too thin or too small, it should be accompanied by a mark containing the mark. The difference between pure gold, pure gold and pure gold: When buying gold jewelry, you must first understand the quality inspection mark of gold jewelry.