Most high quality silver items are stamped with a "fineness" or "quality" mark. This mark designates the precious metal content of the jewelry, and under federal law, must be accompanied by a maker's mark or registered trademark.
Silver Alloys
Because pure silver is so soft, it should only be used when malleability is required, such as in handcrafted jewelry featuring weaving and other intricate designs.
Sterling silver is most often used for jewelry and household accessories because of its combination of beauty and durability. Acceptable quality marks for sterling silver include: sterling, sterling silver, ster and/or .925
Maintenance
With proper care, your fine quality silver will last a lifetime. To minimize scratches and other damage, store your silver jewelry either in a cloth pouch or in a separate compartment in your jewelry box. Avoid exposing your silver to household chemicals when cleaning with bleach or ammonia, or when swimming in chlorinated water, as these chemicals can damage silver.
Care should also be taken to prevent silver tarnish build-up, a dulling that naturally occurs when silver reacts with sulfur or hydrogen sulfide in the ambient air. To clean your silver, use polishes formulated specifically to remove tarnish. You can find fine silver polishes, solutions, or cloths appropriate to remove tarnish at most hardware stores or specialty craft stores. Tarnish is most easily removed when it first becomes visible.
Although wearing your silver jewelry often is the best way to prevent tarnish from building up, regular cleanings of all your silver items will prevent tarnish and keep your silver bright and sparkling.
Look for the fineness mark and the maker's mark on the underside of the silver item you are considering to ensure the quality.