Generally, jewelry bought in specialty stores has the logo of processing factory. For example: emerald jewelry (CL), Baitai jewelry (Baitai thousand gold) and so on. If you lose your certificate and invoice, you can take them to the retail store for cleaning. Some need a little processing fee, and the cost is not high. Brands with good after-sales service can be cleaned and maintained free of charge, such as the products of Baitai Jewelry.