Art Déco ring

A beautiful 14 carat white gold Art Déco set with in the center a brilliant cut diamond (circa 0.55 carat) on a square plaque of onyx, rimmed by brilliant cut diamonds and two baguette cut diamonds (total circa 0.6 carat), with the master’s mark of B.J. Korthagen (1925-1969), circa 1925-1930, The Netherlands.