I've got a jar of Goddards Silver Dip which I used to clean an intricate silver necklace I have. It worked a treat. I bought it either at a supermarket or a hardware store, sorry, but can't remember where!
I cleaned an intricate silver cruet set the other week by putting some bicarb in some hot water in a bowl in the sink together with a piece of silver foil. You must not let the silver touch the foil. Gently agitate with a soft toothbrush and it should come up sparkly.