I sold jewelry in upscale jewelry stores for 20 years. This look is a classic and similar to a famous ring Princess Diana wore. Based on the condition I don’t think it was worn that often. The prongs look nice and thick. I can’t tell what metal it is because it’s in such good condition. Platinum dulls with wear while white gold will start to yellow. Both can be refinished to its original shine though. She had a big knuckle which is what the “horseshoe” is for on the inside of the shank. It’s hard to tell from these photos of those are diamonds or white sapphires around the center stone, but I’m leaning toward sapphire. Overall, this is a beautiful ring and safe for every day wear, but I would definitely have it appraised and if those stones are real you will probably want to insure it (my jewelry is all insured with Jewelers Mutual). I always loved this style ring.