A Victorian crescent brooch set with cabocon cut opals and old cut diamonds in rose gold.  The opals are predominantly blue/green/orange in colour and graduate in size from approx. 6.2mm x 5.5mm at the centre down  to 2.0mm x 3.00mm at each end. Between each opal are pairs of rose cut diamonds set one above the other before terminating with a single diamond at each end.  A bead and rope twist gallery.  Curved pin with hinged fastening to a C scroll catch.  No hallmarks, tests as approx. 9ct gold, with "9ct" marked to the back of the brooch