A portrait miniature and diamond brooch/pendant

The central plaque with a portrait miniature depicting Beatrice Cenci as a Sybil after Guido Reni, to an engraved border, in a surround with alternating collet-set rose-cut diamonds and openwork cartouches, to an engraved bail, millegrain detail throughout, diamonds approx. 1.20 carats total, length 5.2 cm, chain length 49.0cm