Our silver jewelry is made of sterling silver (925 silver) and plated with 18 carat gold. If it is not stated that the jewelry is silver jewelry the jewelry is made of BRASS or environment co and gold plated (ranges from 0.5 to 2 microns) It is especially in contact with water / sea water / pool water / sulfur water or chemicals (for example perfume). In case of yellowing or blackening of 925 silver jewelry they can be cleaned according to the following instructions: Step one – Mix a little dish soap (without lemon) with hot water and dip a cloth in the soapy water. Step Two – Rub the jewelry with the cloth. Third Tuesday – Rinse the jewel with cold water. Step Four – Wipe the jewelry with a clean, dry, soft cloth.