Plz help me research this 1950s (Galanos?) dress

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.

 

Galanos was/is a designer, not a couturier, so at the time he was considered to be more like a manufacturer than an artist. His designs would be made by jobbers - manufacturers who were contracted to make x number of dresses in various sizes to be sold under his label through boutiques and salons that carried quality clothing, and through the department store labels with their own high-end dress shops. Brand recognition mattered more for the stores than designers at the time - but that began to change in the late 1950s as American designers like Galanos and Norell became known and respected. So as you found an example of the exact dress with the label, it's safe to say the design is by Galanos, but your example was sold through Blum's.

 

That's the relationship I wasn't quite understanding, as Blum's wasn't in the label resource and I wasn't sure how common design copying or reworking would have been. Thank you!