First off, I know very little about the subject, but this piece was so beautifully made I had to rescue it from the thrift store. Going by helpful guides I'd guess it's 1950s. It's very heavy material, I think handmade, and has a single label from Blum's Vogue Chicago. Then in my research I ran across this dress in the Met collection that sure looks like the same, down to the ribbon that runs up the sleeves and across the back. The one I have is unfortunately missing the top button (buttonhole is there) and has some staining and a small repair under the arms. Might Blum's have copied the design? How many of those dresses could have been made? I have no idea how to continue my research at this point. I'm not even sure what to call that type of material! There are some detail pics below but I can upload more. Thanks! Edit: Aha, might have found my answer, just took me a while. This dress is also exactly the same but with a different distributor's label instead of Blum's.