Over time your jewelry will tarnish, so I recommend having a good polishing cloth such as this one to keep it shining!  It is a versatile cloth, containing special chemical cleansing agents and non-scratching micro-abrasives, suitable for metal jewelry as well as soft gemstones. It can also be used on chrome, wood, ceramic, hard plastic and glass.  To slow down the natural tarnishing process, keep your jewelry in an airtight place when you are not wearing it (such as a ziploc bag).