This happens during the production process. The main reason is that the module is too small for stamping 925 or 990. What is Sterling Silver .
Sterling Silver Knot Beads 925 Silver Chinese Knot Bead for Bracelet Necklace
20 Sterling Silver Bar Connectors 925 Silver Rectangle Quality Tag for Extension
1 x Padlock Lobster Clasp 925 Silver Gold Plated Clasp 3571-1E
Rectangle 925 Silver Lobster Claw Clasp With Jump Ring for Necklace Jewelry
925 Silver Lobster Claw Clasp w/ Jump Ring Connectors for Jewelry Findings
925 Sterling Silver Ball Clasp Iced Matte 6mm Magnetic Clasp Company Langer
