I purchased the 'clip'/pin below along with some military ribbons in a lot in a thrift store. I do not know anything about it, even if it is military-related or not. Here is an image of the obverse (the pin in question is bottom left; the other items are to show scale):

Here is the reverse:

The hallmark is tiny...here's the best shot I could get of it:

This is my first post to this forum, and hope I have done everything correctly. It was suggested that it is probably American (given the 13 stars and the use of the word 'Sterling' on the reverse) which is why I parked this inquiry here. I have searched the hallmark databases on this and other hallmark sites with no avail. Any guidance would be greatly appreciated. As an aside, if anyone can tell me what this pin/clip was for, that too would be great.
Thanks,
-Daniel
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