Silver has stable chemical properties and strong corrosion resistance. However, sulfur, nitric acid and oxides in natural media such as air have a certain corrosive effect on silver. Silver jewelry may form a layer of black silver sulfide on its surface after being worn for a long time.
Because silver sulfide is gray-black, with the intensification of the reaction, silver sulfide increases and thickens, and the surface color of silver gradually turns from white to yellow to gray, and finally turns black.