Late retailer 1800s, Enameled Brooch from France

This enameled brooch with C clasp and tube hinge is circa 1870s. The tube hinge reached popularity between the 1850s and 1870s, but with the pin projecting slightly from the edge of the brooch, I am inclined to date this more toward the 1870s.

There is some light wear to the gold tone finish (maybe gold-plated?), and it looks like perhaps there was another part attached to the back that may've extended below the actual brooch. (See the last photo and the areas nearest the bottom of the C clasp and bottom of tube hinge plate.)

Dimensions are 1 ¼" x 1 ⅞".

Thank you for looking. retailer