A fine Art Deco sapphire and diamond brooch, 1920s, centring on a circular-cut diamond weighing

A fine Art Deco sapphire and diamond brooch, 1920s, centring on a circular-cut diamond weighing approximately 1.20 carats, within a brooch of plaque design with a stepped outline, pierced with a geometric pattern, pavé-set with circular-cut diamonds and outlined with buff-topped calibré-cut sapphires, mounted in platinum, length 5.8cm, French assay mark for platinum and 18ct gold, French maker's mark AN with jug, case stamped Boucheron