Gold oxidation

Jewelry oxidation or corrosion manifests itself as dull maps, the blackening of gold or discolouration of the surface. 

Pure gold is resistant to oxidation, but other metals present in the alloys used in jewelry making (silver, zinc, copper, etc.) are not. Therefore, the lower the purity of gold, the higher the risk of oxidation. Oxidation of the alloy occurs due to various substances and environments. However, it may not always occur, depending on the specific composition of the alloy, the length of exposure to the substance or environment, etc. Some risk factors include humidity, human sweat, cleaning agents, cosmetics and other chemicals.