An Edwardian black opal and diamond pendant necklace

An Edwardian black opal and diamond pendant necklace, the oval black opal cabochon surrounded by eight-cut diamonds holding a graduated bar of further eight-cut diamonds with pear-shaped black opal cabochon beneath, in white gold and platinum mount on a fine link chain, the clasp stamped '14ct Platinum', the pendant 4.8cms high, 4.9g gross.