Here's a two-metal combo design.  The base wires around this marquise shaped piece of Grey Agate are Sterling Silver, and the smaller wrapping wire bundles are copper...hmmm, sort of interesting.  A thin twisted silver wire runs through the design and adds a bit of texture..
 
Metal has been antiqued, polished and sealed.  Will not darken further or rub off on skin.  No polishing needed.
 
Comes with a 24 " faux antique copper chain.