Tank ring in rose gold, platinum and diamond

Tank ring in 18k rose gold (750/1000) and platinum (950/1000). Five old-cut diamonds: one diamond weighing approximately 0.15 ct; two diamonds weighing approximately 0.26 ct each (approximately 0.13 ct each); and two diamonds weighing approximately 0.12 ct each (approximately 0.06 ct each). Total diamond weight: 0.53 ct. Width at the top: 1.48 cm. Ring size: 55. Total weight: 15.81 g. Hallmarked with an eagle's head and a mascaron. Excellent condition.