An Art Deco gem-set open foliate bar brooch

An Art Deco gem-set open foliate bar brooch, c1925, centred with a sugarloaf emerald and millegrain-set with small circular-cut diamonds, cabochon sapphires and further emeralds, in platinum, the rectangular frame with black enamel decoration and with two square-shaped diamonds to each terminal, white gold pin, stamped with multiple marks including French control marks and initials ST, 5.5cm wide