This miniature portrait is unsigned. It was previously tentatively attributed to James Peale, but this has now been discounted.
According to the previous owner, the sitter is identified as Mary Ball (1753-1803). However, there have been some doubts about this due to the nature of her clothing. Some dated examples wearing clothing of this type need to be located.
As the casework is later than 1790, it is possible that this is a copy made for a family member around 1820-1830. It was relatively common to have multiple copies of a miniature made at a later date, so that different branches of a family had a miniature to keep.
After 1840, such family copies were often made as daguerreotypes.
The Mary Ball claimed is unrelated to the Mary Ball who was George Washington's mother, although there have been incorrect suggestions that this Mary Ball was the third cousin of George Washington.
The Mary Ball who lived from (1753-1803) was the wife of General James Gordon (1739-1810), a revolutionary war general who was captured by the Indians.
Mary's father was Eliphalet Ball, for whom Ballston, Saratoga, NY was named.
The miniature portrait is reproduced on page 21 of the book "Shadows - The Life and Times of Eliphalet Ball, The Founder of the Town of Ballston".
Unfortunately, in the editing of that book, the image of the miniature was reversed, as can be seen in the attached photo.
A "flipped" image of the photograph included in the book is shown here for easier comparison with the original.
For more about the family see History of Ballston, NY
For a photo of Mary Ball's grave, see Gordon, Mary Ball 930