Lady’s vintage 15K gold & platinum crown delicate diamond ring

Lady’s vintage 14k yellow gold delicate diamond ring. This ring consists of a hand chased setting with a platinum crown which contains 1 genuine, round brilliant cut diamond, which has a weight of .50 ct. This diamond has a color grade of  H, and a clarity grade of SI2. This ring is stamped 15k & PLAT and it has an entire weight of 3.2 grams.  This ring is a size 8- 8 1/2, but it can be reasonably altered.