NWT Rare Vintage Find indigo & velvet dress

This is a gem of a vintage find because it's still NWT! It's a lovely cocktail dress with an indigo rayon base that sort of looks more purple when the light hits it in certain way. The details are velvety black floral embroidery all over. Long zipper down the back. Brand: Steppin' Out. Size: 7/8 but please note that sizing was different before! This dress form is 34" by 26" by 35" for reference, so I'd say this is more of a size 4/6 in modern sizing. I'm marking it here as M. Made in the USA.