Used 34 images picked from googling the concept as the dataset, hand captioned mainly considering following categories:

Type: pendant, brooch, mirror, ring

Main object: animal, lady, flower

Gems or techniques: opal, diamond, white matt glaze, verdelite, frosted glass, (carved/baroque) pearl, Plique-a-Jour (transparent) Vitreous Enamel, carved chrysoprase...

Mix and match them with description of the main object you want with natural language seems to give me nice result, going like:

An art nouveau jewellery brooch made of Plique-a-Jour transparent Vitreous Enamel and pearl and yellow diamonds featuring a bouquet of lily of the valley