silver is a chemical element (ag from latin argentum, derived from the greek ὰργὀς: shiny or white) + atomic number 47. pure silver (1000) is soft, to make the metal workable it's mixed with copper resulting in a variety of alloys, all precious matters jewelry are made with sterling silver : 925 parts silver / 75 parts copper
to keep your silver items beautiful make sure to sleep, shower, swim, perform household chores, sport without them.
silver will eventually change from white to black in time. if you don't like this antique patina for your item you could make it shiny + new again with a polishing cloth or silver dip. totally black silver items are oxidized through a chemical process, the blackness is always a very thin layer, it will wear of a bit in time.
2,5 - 3 on the scale of mohs. glossy becomes a bit matte, matte becomes a bit glossy over time.