Rudolf Erdel Platinum and 18KY gold. Hallmarked Plat 950 and 18K, Trademarked OED c RE for Rudolf Erdel. It is a 5mm Montana sapphire weighing 0.64 carats. It is finger size 6.5. There are 18KY gold balls on the ring. It is 3.75 mm wide at the top and 1.85 mm wide at the bottom of the shank. 100-100-214