This is a wonderful example of Deco design done in silver with a central black stone which is prong set.  The dome shaped top and sides are decorated with bead set marcasites.  This is an exquisite vintage piece that can be worn as a clip or can be threaded onto a chain and worn as a pendant. The back of the clip is marked only with the number "800".  This indicates that it was made of 80% silver to 20% base metal and that it likely came from Europe during the 1930's or 40's.  Measures 1 1/4" long.  SORRY. THIS ITEM HAS ALREADY BEEN SOLD!