An Australian opal diamond and paste bar brooch, by J.J. Williams, Charters Towers, circa 1880, set with a solid opal matrix surrounded by ten old mine cut diamonds on a double bar set with ten further diamonds and blue garnet topped doublets, twice marked 'J.J.W/15c', 15 carat yellow gold, fitted blue felt box with gilt lettering. Reference: illustrated K.Cavill,G.Cocks and J.Grace Australian Jewellers Gold & Silversmiths-Makers & Marks,1992, Plate 354