Fostoria American Egg ?? Rare ??

When I purchased this I was told it was Fostoria and that the owner saw one like it sell at auction for $800.00. The glass is the same high quality and weight of Fostoria. Perfect condition. Egg has16 rays common to Fostoria on top and bottom that are not visible in the photos. I know Fostoria made some unusual pieces that were never marketed but I don't know if an egg was one of them (other than the one made for Avon). If you are aware of another manufacturer that made this pattern please advise me. Thanks