Rare Vintage Lingerie Top Baby Blue Unsized

Very RARE vintage lingerie top (I would wear as a regular tank with jeans or cute slacks). This shirt has been VERY well taken care of based on the age. It is a beautiful light shiny blue with tiny delicate flowers down the front. No name brand or tags. I estimate a Medium, but has stretch. I normally wear a small and like the loose fit. Pics included w/measurements. A few places seem to have a change in material (not even sure how to describe). I took pics, but can’t really notice it in them❤️