If you are at all interested in the history of costume jewellery and its relationship to fine jewellery, values, and when is a copy not really a copy, I encourage you to read the articles written by jewellery historian and collector Robin Deutsch for Costume Jewelry Collectors International.
Two of the three pieces she has written have been posted, and you can find them here. It’s a great read on a great site. The photo below shows a repro of a famed Boucher enamel piece, discussed in the first article, The Piece of Your Dreams … Or Is It?.

Thank you very much for sharing