um….i cant quote the source, but i heard that since one of the reasons for tznius is to protect the men, it goes by the men in your community.
if ur wearing stockings in a community that the men assume your wearing stockings EVEN IF ITS VERY SHEER…than your allowed to wear any denier cuz the men won’t think that your not wearing stockings if it doesnt look like it…
but, if lets say you’re in a community where only stockings with seams are worn, than u may only wear seams, cuz the men will assume that if you dont have seams then your not wearing anything…;)