Entourage ring with moonstone and diamonds

Description:

Probably USA, around 1920-1930
RM 55
Yellow and white gold 14 K (585), stamped. Hallmark. 20 octagonal diamonds, total ca. 0,20 ct. 1 cabochon cut moonstone of ca. 10 ct, Royal Blue. Ca. 8,4 g. The condition of the ring is very good.
From an Austrian private collection.