Pure silver is defined as 99.9% pure silver, but it is too soft for most uses. And 925 sterling silver is actually a silver alloy. 925 sterling silver contains 92.5% silver, and the remaining 7.5% is another metal, the most common being copper. Adding a lower-cost metal-used to harden the resulting alloy so that the metal can be cast into a shape that will remain unchanged during use.
Pure silver loses its luster as long as it comes in contact with air.
Pure silver, like gold, does not discolor or oxidize on the surface.
It is an alloy metal that attracts corrosion.
Rub a piece of visibly shiny sterling silver with your thumb,
and you may find faint smudges on your skin,
which indicates that 925 sterling silver is beginning to lose its luster.
Your 925 sterling silver only needs to be polished regularly with a cotton cloth to keep it shiny.
925 sterling silver that has not been used for a period of time may have a significant rust and requires polishing paste.
In addition to polishing paste, you can also try the following techniques.
Put the tin box in the sink, fill it with hot water, and add some salt and baking soda. The ratio is not important here, just put a few teaspoons. Next, put the silver into the water so that the silver flakes are in contact with each other and the tin foil. The rust will peel from the silver to the foil, and if the rust is severe, you will be able to see it peeling off. Leave it for no more than five minutes, rinse and dry.