Sterling Silver by definition is .925 silver. It is a great silver option for those who don't wear gold. Sterling silver will tarnish from oxidation but with the proper care and cleaning can be brought back to a perfect shine.
Remove jewelry when sleeping, exercising, or doing other physically strenuous activities. Avoid contact with perfumes, body oils, and other chemicals, including household cleaners. Never use chemical cleaners as these will do more harm than good; for light cleaning, gently polish with a soft cloth and store your beloved jewelry in a cool dry place.