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It’s a lovely necklace. I had no luck with the hallmark, but single initial hallmarks can be hard to figure out. Hopefully someone with more resources will have better luck. Do you know when and where your aunt bought them? Very pretty turquoise, but I don’t really have a guess which mine it could be from.
This piece on eBay is rather similar in many respects. (The seller says theirs is signed, but squint as I might, I can’t make out any marks on the back of it.)
I think you’re probably correct. One of these perhaps (the 2 without other marks)? And I think Jane Popovitch is not Navajo; the site has that wrong? But maybe I’m getting that all mixed up with something else I read on this site…
I think you’re on to something about a conjoined “JP” hallmark @Islandmomma on the OP’s necklace. I can definitely see that now. Hougart’s 3rd edition NA/SW hallmarks book has a few “JP” hallmarks but, they’re not an identical match to this one.