1940s French diamond and sapphire spiral ring in 18kt yellow gold

1940s French diamond and sapphire spiral ring in 18kt yellow gold. Centred with nineteen round brilliant cut diamonds in platinum grain settings, surrounded by a swirling row of round mixed cut sapphires in four claw settings, to a spiralling cluster design with a central bombe cluster, curving claws, deep ridged twirling skirt and crossover shoulders which terminate to a solid shank. Hallmarked 18kt gold, French.