Why did your gold jewelry fade?

After wearing gold jewelry for a period of time, people found it change color or fading. Many people thought this is the fineness of gold jewelry insufficient. So they went to the store or the Consumers Association to complain, but it was told that the fading of gold personalized pet photo necklace[https://www.custom-necklace.com/precious-personalized-pet-memorial-photo-necklace] jewelry is not the was not the insufficient of fineness. So, what are the reasons for this? What materials will make the gold jewelry fade?
Some of the sweat is a waste and harmful substances in the human body. When these materials come into contact with silver and copper in gold cheap name bracelets jewelry[https://www.custom-necklace.com/], they will chemically react to produce silver chloride and copper sulfide, which will cause discoloration or fading of the jewelry.
When silver and copper in gold jewelry come into contact, it produces silver chloride and copper sulphide, and exhibits a deep black chemical salt. This chemical salt often falls from gold jewelry, contaminating the wearer’s skin, leaving a very noticeable black stain on the skin.