Her German Wikipedia article is here.
The large cuffs lend a retro look to Friederike's dress. Her dress appears to have a brocade stomacher panel framed by what appear to be embroidered rever strips.
Keywords: Friederike von Sachsen Gotha Altenburg, Wettin family, Duchess, German, straight coiffure, square neckline, modesty piece, stomacher, revers, elbow length full sleeves, cuffs, under-sleeves, engageantes, vee waistline, full skirt, neck band, earrings, bracelets, robes