This is a intresting piece to say the least, not sure how one could verify date, history or manufacture for it appears to have no markings. It appears to be copper also, like the art design on it. Appears to be a Art Novae period art to me. I would also say it was made for use as a medallion to be place in a neckless. Again without marks, all this would be hard to place in facts. You will have to determine clues through the Art. Value on a piece like this can only really be determined by the price 2 people are willing to pay.