I wouldn’t call this a dress, nor would I call it a skirt:
The garment was initially intended to be worn as a skirt, but Middleton instead wore it as a short dress. She wore black lingerie underneath. [Kate Middleton’s See-Through Dress to Be Sold – CNS News]
Obviously, someone will bid for it and win it, but would anyone ever wear this in public? Privacy of your own home, sure, but not in public.