Vintage 1 piece dress 60's

I believe this dress to be from the late 50's or 60's it was made by the International Ladies Garment Workers Union Which closed its doors in 1972 . This was lot 6 , Size 9 . Ladies . It is a Small Size 9 . It has a zip up back with a tiny eye hook at the top the metal hook is in place and well sewn in . It has a built in slip in the skirt part and is all one piece with bell 3 quarter length sleeves . Beautiful peach/cream lace over a periwinkle blue satin