It is a lovely suit! I think late 50s, and I'm in agreement with Nicole and Barbara about the possibility of there having been alterations, to the collar and to whatever bit it is that's showing in the last photo. Like Nicole, I can't tell what "part" that is, but it looks to have been taken in. Or folded over, or something.
I would guess the fabric is a linen/silk blend. I have several pieces from that time period that have the same look to the fabric--like a linen weave but softer and with the luster of silk--that I've burn tested, and they test out, to best guess, like linen and silk.