Vintage emerald green gown size 6 (4?)

Remarkable condition, Had to look hard to find a small thread pull ( see photo) less than 2 inches long and not noticeable at all. Says size 6 but measure to be sure because no returns. Pit to pit 16", waist 12.5 inches, sleeve 25 inches, 57" long. Nylon with sweetheart neckline on inside piece which is a darker more olive green. Really Beautiful and great shape. No brand but union tag.#467