From Wikimedia.
Sophia Alexandrovna Urusova's dress has a diaphanous upper bodice split by a vee neckline with a ruff, a Renaissance retro touch, with a pelisse bodice, puffed sleeves, and wide belt. The diamond pattern and the ridges expanding from her pelisse bodice to form something like rolled sleeves are also Renaissance touches.
Keywords: 1827, Sokolov, Sofia Urusova Radziwill, Urusov family, Radziwill family, Princess, Russian, curly coiffure, Apollo knot, partlet, vee neckline, ruff, bodice, trapezoidal neckline, pelisse bodice, revers, puffed sleeves, belt, full skirt, earrings