This is a very appealing miniature portrait and is painted by a very skilled artist. Unfortunately it is unsigned. Various artists have been considered, but at present Moses B Russell or Thomas Badger (as discussed below) are seen as the most likely. In favor of Moses B Russell are the pose, the background color, and the facial style as appearing in a well signed miniature by Moses B Russell at Russell, Moses B - portrait of a young lady...Notice also the size of the two waists.
Judging by her clothing it would seem to have been painted around 1845. The vendor was unable to help with provenance as the portrait was found loose within the pages of a scrapbook previously belonging to a rare book dealer. It appearing just to have been put between the pages to protect it.
It has been hard to find examples painted in a similar style in any of the reference books.
There are some similarities with portraits by Charles Fraser, such as the miniature of Ann Dickinson LaBorde on page 64 of the CAA catalogue, where the body shape, pose, and quality of detail looks similar.
The pose is also similar to that of Mary Theodora Ford, color plate VI and page 65 in that catalogue, although without having the vegetation in the background. However, overall it seems a little too bright and cheerful when compared to most of Fraser's work.
Another possibility is Thomas Badger. An example by him can be seen as fig 211 in Johnson (although there that miniature is attributed to Mrs Russell).
The sitter is unknown. 1243