A genealogical sketch of her is here. Her mother-in-law was Alexandra Dietrichstein, née Shuvalova.
From wikimedia.
It is hard to say what her dress is made of. Her neckline would work for the next thirty years, but the sleeves and belted waistline would not.
Keywords: 1828, Kreihuber, Wratislav von Mirowitz family, von Dietrichstein family, Countess, Princess, Austrian, curly coiffure, knotted coiffure, Apollo knot, floral headdress, off shoulder vee neckline, pleated bodice, dual upper puffed sleeves, cuffs, belt, jeweled buckle, natural waistline, earrings, bracelets, wrap