A biographical writeup about her in Italian can be found here.
From Wkimedia. Photo - Ji-Elle; lightness added to image with Photoshop.
Marie Angelique's dressmaker used striped cloth panels and ruched strips plus a complimentary translucent material for her modesty piece and striped bows for the dress she wears for this picture.
Keyword: 1778, Huin, Ji-Elle, high straight coiffure, cap, ruffles, bows, scarf, scoop neckline, modesty piece, bertha, bows, tent bodice, ruching, close sleeves