Excellent to very good condition for age and type. Painting is done in gouache or watercolor. You can see a little crack/loss to the outer portion of the panel upon which she is painted. When she is in l frame, those minor flaws do not show. Frame is typical of the era c. 1810- 1950, and fashion would put her about c.1830-35.
About portrait miniatures and miniature paintings: There are two types of miniature portrait or painting. Prior to the invention of photography (1838's Daguerreotype), the only way to preserve a likeness was to sit for an artist's original portrait, or to have your likeness carved in wax, wood, or sometimes terra cotta or ivory. The miniature portrait industry was one mostly reserved for the well-to- do, though lesser sketches in pastel, conte crayon, charcoal, or pencil also survive on a more common level - usually done by a family member. These survive as masterpieces in miniature, quite often, and a one of a kind treasure. So there are the ones that are not made as souvenirs of famous paintings and portraits (often noted as 'apres' or after the work of such-and-such artist, and often recognized and reproduced in numbers for tourist trade of 18th - 19th century), Those are personal, usually far more delicately detailed, and represent original works of art that are collected, sometimes signed by the artists who practiced portraiture in miniature. They might be the only image a parent would have after the marriage of their daughter, whose marriage took her far from home. Or the image given to a betrothed, or as political offering or to show a prospective spouse in another country just whom he or she was proposed to by family/political union. They are history in testate and should survive for hundreds of years to come, the only remainder of a