This is an vintage, 20th century doublet ring with a flat carved oval form black opal in a 9ct gold setting. Doublet rings have the natural stone, thinly 'sliced' and placed atop and center with a synthetic backing to help bring out the brilliance of the opal character. The setting is Modernist in style with a solid backing. The estimate is based on actual recent past recorded auction sales of comparables. Retail 'asking prices' may be higher and vary.