Art Nouveau Style Mother-of-Pearl and Opalite Pendant Necklace with Marcasites

This exquisite piece is a pendant necklace featuring a central, large, cabochon-cut mother-of-pearl or moonstone, displaying a soft, iridescent sheen. The main circular stone is bezel-set within an ornate frame of darkened silver-tone metal, possibly sterling silver with an antique patina, or gunmetal, detailed with numerous small, faceted marcasite stones that add sparkle and texture. The frame itself has a scalloped, almost floral or sunburst-like design around the central stone. Above the main pendant, there is an intricately designed bow motif, also studded with marcasites, with a smaller, round opalite cabochon set in its center, exhibiting a vibrant play-of-color. Below the main pendant, two additional small, round opalite cabochons are vertically suspended, creating a delicate drop design. The entire pendant is attached to a linked chain, consistent in color and finish with the pendant's metalwork, suggesting it is an original pairing. The craftsmanship appears to be detailed, indicating a quality piece, possibly from the late 19th to early 20th century, embodying characteristics of Art Nouveau or Edwardian era jewelry, though it could also be a vintage revival piece. There are no immediately obvious condition issues like significant damage or missing stones visible from the image, but the dark patina on the metal could be original oxidation or tarnishing. The overall aesthetic is elegant and antique-inspired.