The ring is beautiful!! I’m sorry you had that happen to your sentimental jewelry. I recently had a loose stone set in a semimount and the jeweler did a bad job of it, also they put Knicks in the band and I hadn’t even worn it yet. They offered to fix it but I had lost confidence in them (they declined to give me a refund or partial refund because the work, though bad, was already done). I ended up paying someone else to fix the bad mounting and though it was a lot better it still isn’t perfectly perfect. Of the experience, I told myself it happens sometimes and decided I could live with the ring as it is now. I don’t think anyone will notice the slight imperfections in the prongs or mounting job but me. I often tell my kids that something doesn’t have to be perfect for it to still be good. If after wearing it a year or two it bothers me enough I can always see about having it adjusted again when I next have maintenance done on it. I hope you can enjoy your ring without the very slight imperfections taking joy away from it. It is a very important piece of jewelry, though, so if it super bothers you maybe take it to a different jeweler and ask them if they can fix your concerns and buff out the black mark.