Tank ring in yellow gold, platinum and diamonds

1940 ring in 18k yellow gold (750/1000) and platinum (950/1000). Set with eight old-cut and rose-cut diamonds. The two central diamonds are approximately 0.23 carats each, and the six side diamonds are approximately 0.03 carats each. Total diamond weight: approximately 0.64 carats. Width at the top: 1.5 cm. Ring size: 54. Total weight: 9.27 g. Owl and mascaron hallmarks. Excellent condition.