A reader wrote in with a question about a piece of pottery. He owned a small hand-painted planter: "Roseville is the name and some other things are printed in raised lettering."

I determined that he had a piece of Robinson-Ransbottom Pottery, or RRPCo. His piece was probably of recent manufacture (RRPCo is still making pottery) and worth very little. Although some pieces of RRPCo are gaining in value, most are still not highly desired by collectors.

Because RRPCo is in Roseville Ohio, and they mark their pieces "RRPCo - Roseville," many people have been tricked into thinking they own "THE ROSEVILLE." This is a common misperception, and can potentially be an expensive one.

Roseville is generally marked just "Roseville" with a shape number, something like "123-9" or with a plain, capital R. If you see RRPCo, it isn't "The Roseville" which everyone talks about. To research Roseville marks, you must go to the books, there is no single source online. The best information about the marks that were used by Roseville is in "The Collector's Encyclopedia of Roseville Pottery" by Sharon and Bob Huxford.

Editor's Note: We've found this to be a useful site: http://www.ohioriverpottery.com/roseville_exchange/roseville.html