This looks like a Stieler portrait.
From pinterest.com/pin/572379433866616674/ via pinterest.com/ajackson1912/-burgundy/?lp=true; enlarged by half. Also posted to Marie of Saxe-Altenburg, Queen of Hanover’s Subalbum here.
Marie wears a conventional evening dress with an off shoulder vee waistline and pleated bertha.
Keywords: Queen Marie of Hanover, Marie von Sachsen-Altenburg, Alexandrine Marie Wilhelmine Katharine Charlotte Therese Henriette Luise Pauline Elisabeth Friederike Georgine von Sachsen-Altenburg, Prinzessin von Sachsen-Altenburg, Königin von Hannover, Wettin family, Welf family, Princess, Queen, German, straight coiffure, lace floral headdress, earrings, necklace, chemise, modesty piece, off shoulder vee neckline, fitted bodice, pleated bertha, brooch, quarter length tight sleeves, lace cuffs, bracelets, clasps, vee waistline, full skirt, wrap