Never seen it before, but it's very pretty. The clips worry me; I presume they're just for trying it on, and the finished product will either have a zipper or fasten like a corset?
Looks to me like a corset in the back?...it looks like there are "buttons" along the left side and I'm thinking those strings are used to lace it?
OP, that is gorgeous, I am unsure on that dress specifically but I found a few look alikes:
I would got to a local salon or two with that photo when you go to try on dresses. Someone may know that specific dress, or they could at least find one that is similar for you to try on. You may love it, but you may end up in something completely different anyway. Good luck!