|A miniature pendant with a portrait of Louis Charles de France, or Louis XVII, by an unidentified artist. After a portrait by Vigee-Lebrun. [source: Adjug'art Auctions, via Auction.fr]
The 19th century was certainly no stranger to Bourbon nostalgia, and this miniature portrait of Louis Charles de France--known to many royalists as Louis XVII--is certainly no exception. Although the piece does not have a definite date, the auction house dates it to the early 19th century. It's a plausible enough date, and it's possible that the piece was produced around the time of the Bourbon Restoration or perhaps several years after the Restoration.
The Bourbon Restoration made it vogue to reproduce images of the monarchy--including images of the now-deceased members who had gone from loathed figures in the revolutionary to exalted martyrs under the Restoration. One can easily imagine this brooch pinned on the jacket or bodice of a royalist in the early years of the Restoration or beyond.