1.23 Carat Old Mine Cut Art Deco Platinum Set 18K Ring Shank Diamond & Beautiful Sapphires Halo Ring. The ring is a brilliant J color SI-1 clarity. It throws a lot of light and brilliance. It has a diameter across the face of the ring of 12.2 mm. Ring size 7-3/4, weight 3.4 grams The ring is in excellent condition and looks more like a 2 carat diamond than a 1.23. The weight of the diamond 1.23 is inscribed on the inside of the ring shank.