10K thunderbird or phoenix pin please help w/maker's mark id

[bradrainie]

Hi, I have this thunderbird or phoenix pin and believe it to be 10K. It was tested for 10K and was positive. There is a mark on the back, I believe it to be the maker's mark, but am unsure of the origin. I was thinking it was middle east but have found no reference to this mark on this board or any other site. Please help. Thanks!

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