A late Victorian opal and diamond tiara/necklace, consisting of seven knife-edge gold bars graduating from the centre, each set with two round cabochon-cut opals and an old-cut diamond in-between, the bars connected with six diamond-set arches each arch with a diamond-trefoil and a round cabochon-cut opal within, terminating on each side with a small diamond and opal trefoil motif, the diamonds estimated to weigh 2.9 carats in total, all mounted in gold and silver, attached to silver-gilt…