Real or Repro?

I've been busily cleaning and organizing and researching...all in a day's work when getting ready to open a vintage shop on Etsy. I realized recently that I have a significant fear of listing something that I believe to be vintage, only to find out that I was wrong and that it is not.

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I'm confident in my spotting skills, for the most part. But every once in awhile I run into something like this beautiful salt cellar. I found a set of five, they all still have their stickers inside, and I cannot for the life of me get anywhere in my research to find out their authenticity.

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Can anyone recommend a resource? Do you have an opinion? What would you do? Help!