Vintage gunmetal gray sleeveless dress

Vintage gunmetal gray sleeveless dress with 2-piece look; slight silvery sparkle to fabric in light! Difficult to catch in photos.. unique collar & 3 large buttons that can open to reveal zipper opening. Chest measures 18” when lmeasured flat from pit to pit. Has 17” long zipper in front hidden underneath button area! Waist measures 14/15” across flat. Pit to bottom hem measures 33”. Garment is marked size 16 which is more like a 12? in vintage garments. (From late 50’s)