To maintain the beauty and integrity of pearls, regular proper care should be part of your regime.  It's easy to scratch pearls and daily contact with skin oils causes them to deteriorate.  First, find a soft jewelry cloth made of cotton or bamboo.  Never use any abrasives like a toothbrush or a plastic sponge.  Dampen the cloth with water and begin wiping each individual pearl until your strand is clean.  If the clasp has to be cleaned use a q-tip bud with water to remove any dirt or residue.  Aside from cleaning, wipe your pearl jewelry gently to remove oils and perspiration before putting it away