Woodbridge Antiques has dated this piece to the 1920s.
Hallmarked Birmingham 1919 by Albert Carter. There is a good fastening clasp at the back.

A perfect gift, made by a collectable designer and in lovely condition (slight wear to enamel on body). Would be a great addition for a collector of butterfly brooches.
Measurements: Width: 4 cm Height: 1.9 cm Weight: 4 grams
Weights and measurements are approximate.
Stock Code 41792
Woodbridge Antiques has dated this piece to the 1920s.
Specialists in quality antique silver, fine jewellery & accessories
You can view the stock and full dealer information on the Woodbridge Antiques Profile Page