Silver has been known as the moon metal and is a stabilizer and securer of the action of the gemstone's energy.  Like a mother to a stone, it does not expand the energy of the stone, but rather acts as an existing support to the stone's properties.  Silver will reflect an individual's self-esteem and therefore can encourage the personality of the gemstone itself.  Gems that are set in silver are supported with the silver ore energy rather than stimulated as with that of gold.