I haven't seen a brooch with that pretty flower-stamped back--it's lovely!
If you look at the portrait of the woman through a loupe or other strong magnification, you can verify whether its a transfer or a handpainted portrait (in general more valuable, since it's essentially a miniature work of art!)
In contrast to the (irregularly placed) brush marks of something handpainted, a transfer has a regular pattern of dots over the surface (though, to complicate matters, sometimes brush strokes are placed on top of those, to make the portrait appear hand-done!)
It looks like a variation on a cameo habille, which showed an idealized woman wearing jewelry (a pendant "necklace" with a rhinestone or diamond in it, or "earrings").