Vera Wang uses a standard heavy plastic coiled zipper, not an invisible one, when the fabric is heavy. This gown is shirred. An invisible zipper will not work because the turn of the cloth is too thick. It will never slide up. And, even if you would manage to sew it far enough away from the teeth of the zipper so that it could slide, that step would cost you the invisibility. The fabric would pull apart and expose the zipper anyway.
So, Vera uses a standard zipper with a topstitched application on her ready-to-wear White line.
And, as a special touch, she lines the zipper with petersham (soft grosgrain) to keep the zipper teeth away from the bride’s skin.