Hann, you could google "Certificate of Authenticity." See what comes up. I also saw a link to a CofA via the ebay art community "chat" room. My watercolor teacher sells many originals. On the back of each painting is a CofA. It says that she is the one true artist and that this painting is not a reproduction. I would not worry about that myself because no one is likely to want to reproduce my production!
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