1920s Amethyst & Diamond Oval Cluster Ring in Platinum on 18kt Yellow Gold

1920s amethyst and diamond oval cluster ring in platinum on 18kt yellow gold. Set with an estimated 7.20ct oval mixed cut amethyst in a grain setting, encircled by a row of round old cut diamonds in grain settings, to a large oval cluster with fancy carved gallery, diamond set shoulders which smooth to a solid square shank. Hallmarked 18kt gold, French.