Very nice used condition, vintage zipper works great.  Some age fading around zipper top and some age marks on bottom of dress, I used a baby wipe on one stain and it was gone, so these are easily cleaned.  Beautiful dress, reminds me of the mom of the Donna Reed show.   Very vintage, beautiful.   I would guess 50s or 60s.   I am guessing size at Small or extra small.  Material like a shiny heavy linen?