If this was a custom rather than an un-tagged couture piece, the maker deserved a medal.
There are four pieces to this dress. First, the dress itself--heavy black satin, unlined, a wide, shallow scoop neck in front and a V in back, Short dolman sleeves, a side metal zip. The skirt is carefully darted to give it its fullness, with a back kick for extra leg room, and an ingenious collection of snaps and hooks include those that hold on a pleated back train (!) the same length of the skirt (last pic). The cummerbund ties the two things together.
However, the train can come off and be replaced with a gathered over-skirt of galloon lace, the cummerbund snapped back in place, the result being a totally different look. That's a lot of looks for just one dress.
The waist is 26", bust around 36", and it measures 8" from the back neck to the waist and 32" from waist to hem. All in all, an ultimate Little Black Dress.