Art Nouveau brooch-pendant

An Art Nouveau opal, diamond, ruby, enamel and gold brooch/pendant, by Antoine Bricteux.
Designed as a gold plaque, depicting flowers set with rose-cut rubies and diamonds within a chased gold frame of branches and leaves set with a marquise cut cabochon opal, suspending an old mine cut diamond and a drop cut cabochon opal.
The mounting of the brooch is detachable so the brooch can be worn as a pendant.
Circa 1900, with French assay marks and jewellery maker's mark for Antoine Bricteux.