Large Antique ART NOUVEAU Necklace PENDANT Amethyst STONE Victorian

I purchased several pieces of interesting old jewelry at a recent estate sale. For auction is this gorgeous antique Art Nouveau era necklace pendant. No chain. Pendant measures 1 3/4" x 1 1/8", not including the bail. Appears to be silver plated over copper. Ornate design. No damage and very little age discoloration. Unsigned.