14K Gold Ring Genuine Opal Diamond Halo IAG Certified Gemstones woman??s Retro Large Oval Opal and Diamond Halo Cocktail Ring For Sale at 1stDibs Beautiful Black Opal and Halo Diamond Engagement Ring 18K Yellow Gold Retro Large Oval Opal and Diamond Halo Cocktail Ring For Sale at 1stDibs Opal Double Halo Diamond Gold Ring at 1stDibs. An unusual dress ring containing a large oval white opal, 11. 7x8. 3mm. Has an excellent 'play' of colour, and easily seen flashes of various colours, fireglow orange, electric blue, and peacock green. In a rim setting. Each shoulder in this cross over design is set with two 1. 3mm brilliant cut white diamonds, channel set. Head height 12mm, width including the shoulders 15. 5mm, depth 4mm, weight 4. 4grams. The shank is stamped 18K, and tests as 18 carat white gold. Indicates that this ring was manufactured overseas so no UK hallmarks. A lovely ring to own as the play of colour is quite fascinating. Size P, we can resize free of charge.