From the lost gallery's photostream on flickr; a spot and a smudge in the background were removed with Photoshop.
This photo is very difficult to date. However, her dress has a natural waistline and probably has a waist band, suggesting the late 1860s. This could also be from ten or more years later based on what may be a draped tablier.
Keywords: Infanta Antonia of Portugal, Braganza family, Hohenzollern family, Infanta, Princess, German, curly coiffure, off shoulder straight neckline, modesty piece, bertha, lace, tight cap sleeves, tassels, natural waistline, close skirt, order bows, necklace, earrings, bracelets, fan