Silver bracelets turn black when worn. One of the important factors is that there is a great affinity between silver ions and sulfur ions, which is easy to produce chemical reactions. As a result of the reaction, silver sulfide is produced on the silver surface. Because silver sulfide is grayish black, with the increase of silver sulfide, the surface color of silver gradually changes from white to yellow, then to gray, and finally to black. This chemical change can occur in a very small amount, as long as silver meets hydrogen sulfide gas or sulfur ions in the air in the range of trillions to hundreds of trillions, this chemical reaction will occur. Human sweat also contains sulfur, and contact with silver products will make silver discolor, especially the hydrogen sulfide produced by sewage and garbage discharge in urban air is even more amazing, so it is not surprising that silver discolors.