I have in my possession what appears to be a diamond ring set in 90% platinum, but I am not sure. Inside the ring, it says PT900, 51 and 102. I've done my research and found that PT900 means 90% platinum, but can't figure out what the 51 and 102 mean. The ring appears to have one large diamond, and multiple smaller ones around the edge, and since it's set in platinum it gives me the impression that it really could be a diamond. I have almost no information about this ring so I was looking for advice. Here is a photo of the ring. Can anyone help? I'm new here, so sorry if I posted in the wrong place.

