AMAZING vintage chocolate brown sheath dress with bow and pleat collar

Look at this amazing dress! Chocolate brown with pleated sheer collar (made of a very light muslin or linen? It’s not chiffon, it’s something hardier but still incredibly light) and a velvet bow. Seams are so flattering for. GUC, would be EUC but there’s a faint stain near the hem on the back (see pics) which I have not tried to remove but it’s tough to spot unless you’re looking for it. S/M, see pics