AN ART DECO DIAMOND, COLOURED DIAMOND AND ONYX BROOCH, BY OSTERTAG

AN ART DECO DIAMOND, COLOURED DIAMOND AND ONYX BROOCH, BY OSTERTAG
Designed as two shield-shaped openwork diamond-set motifs, each centering upon a pear-shaped cabochon onyx and gathered by a yellow cushion-shaped collet-set diamond on a diamond bombé connecting link, circa 1925, 7.2 cm, with French assay marks for platinum and gold
Signed Ostertag France
Please note that the coloured diamond has not been tested for natural colour