Her biographical information can be found here.
From Wikimedia; removed spots and fixed the upper left corner and adjacent edges.
Alexandra Laval wears an early 1820s dress with embellished dual upper puffed sleeves and a wide-brimmed hat in this Guérin portrait.
Keywords: Guérin, Alexandra Laval, Kozitsky family, Laval family, Countess, Russian, curly coiffure, feathered hat, choker neck band, off shoulder bateau neckline, dual upper puffed sleeves, waist band, Empire low waistline, close skirt, rings, wrap