Prehnite & Black Rondelle Faceted  Gemstone Beads  with  a Prehnite Pendant   Findings are  Sterling Silver, Toggle clasp
 Necklace is 17," Pendant is trimmed in silver.  No markings, I think the  black beads are onyx, possibly Jet, can't remember 
I used to make Jewelry and this is one left from a show. Never worn, The silver findings have tarnished a bit but a lovely necklace.