The bluish discolouration arises because 14- or 18-carat gold contains alloy components that oxidise over time. In most cases the deposit can already be removed with a moist cleaning cloth; alternatively a silver-cleaning cloth works, which however should not be used too intensively, since it simultaneously slightly wears off the platinum plating. Dipping fluid for silver was not tested and is therefore not recommended. As a preventive measure, regular light cleaning without aggressive material removal helps.