"Portrait of a lady (Maria Mancini?) in arms with helmet in hand", Justus Sustermans
So-called portrait of marie mancini (1639-1715), but is probably a depiction of her sister hortense mancini (1646-1699). Identification proposed by user ecummenic (talk) based on the comparison with some portraits of hortense mancini (see images below) and the lack of physical resemblance of the sitter of this portrait to verified representations of marie mancini. Date: 17th century. Dimensions: height: 73 cm (28.7 in); width: 57 cm (22.4 in). Medium: oil on canvas. Collection: Unidentified location. Circle of Sustermans - Ritratto di dama (Maria Mancini?) in armi con elmo in mano