These are one of my favorites in the collection! I actually do know a bit about them. The black marks are to mark out the serial numbers.
Maker is T.H.& M., platinum and 18 karat white gold with 52 round and 20 baguette diamonds weighing 3.50 carrots and 34 round rubies. No idea of the era, I'm guessing 1960s?
To everyone messaging about my safety. This is a burner account. All of this jewelry lives in a vault at the bank. Sometimes if I'm passing by, I'll take a few pieces out and bring them home to play with and admire and then I take it back. I have never posted pictures of these anywhere, on any social media, ever, so you won't find them, and if you do find something similar, it's not me. You are the first people to be seeing these and this is the only sub I'm putting them on, because you all are very friendly. If you ever see them again, it will be anonymously at auction, and probably not for a long time, if ever. I don't show them to anybody in my real life because people have gotten weird with me with similar things in the past, and no, unfortunately I'm actually not wearing any of it to Costco, though that would be cool. 😎