Antique Australian opal &9ct rose gold bar brooch unmarked. Approx weight 3 grams, opal size 8 x 5 mm, strong play of colour, possibly backed doublet on potch, tests as 9ct, unmarked. Approx weight 3 grams, opal size 8 x 5 mm, strong play of colour, possibly backed doublet on potch, tests as 9ct