Gillers Antiques Ltd has dated this piece to the Victorian era.
The reverse has a C-clasp which were in use till 1910's, as well as the original safety chain.

The portrait depicts a courtly lady in profile, dressed in 18th century attire. The luminous hand-painted design in brilliant blue hues against a black enamel backdrop showcases the intricate and highly-prized Limoges technique. The costume is accented with pink roses and subtle gilding. Multiple firings bring out the radiant colours, making it a glimmering work of art.

The portrait is signed "GH".
Origin: Limoges, France
Date: c. 1890's
22 g
5.5 x 5 x 1 cm brooch
4 x 3 cm portrait
Very good antique condition. Small chip to base of portrait; the top and bottom of the inner frame are a bit depressed; small chip to enamel on reverse; tiny dings to frame
Gillers Antiques Ltd has dated this piece to the Victorian era.
You can view the stock and full dealer information on the Gillers Antiques Ltd Profile Page