• (1) Pollution and Oxidation

The chemical properties of silver are active, and it is easy to react with chemicals containing sulfur and other elements to generate sulfur and silver compounds. After a long time, this compound will form a black silver sulfide film on the surface of silver jewelry, which begins to appear as some fine spots, and then gradually diffuses into pieces, which is silver scale or silver spot affecting the color of the surface of silver jewelry, commonly known as oxidation.

Improper wearing or storage of silver jewelry, in a strong oxidizing environment (newly decorated formaldehyde exceeding the standard, etc.) or contaminated with strong oxides, will cause oxidation on the surface of silverware. If the silver jewelry is not worn frequently, and it is not sealed and stored after taken off, the silver jewelry will also combine with sulfur dioxide in the air to undergo a natural oxidation reaction and turn black.

• (2) Physical Factors

Personal Constitution: Some people have more acid in sweat, and some people have less sulfur content. Acid physique wearing silver jewelry is easy to turn silver jewelry black, so different people wearing it, will produce different results. Some people wear it for a few days, then it may turn black, while for others it may turn increasingly brighter. Because silver jewelry is particularly sensitive to the environment, when the ambient air is not up to standard, silver jewelry will be easier to oxidize, so in ancient times, silver jewelry was used to test whether the contact was poisonous.