Beautiful, classy midnight blue silk knit vintage evening gown could also work as a 1930s gown as it is very similar in style. I don't know the exact era of this gown, but it is probably from the 60s or 70s. 

This dress is a stretch silk knit with an invisible zipper back closure. It has tight-fitting long set-in sleeves. The best detail is the sheer "fishtail" hemline, which really couldn't be captured in the photos. It has an attached long silk chiffon scarf at the neck.

It is lined in silk and the label is "Richilene."
Richilene was a small New York couture house known for its custom made evening gowns and cocktail dresses.

Marked Size: none (it could fit 8-12 based on the measurements and style)

 Excellent cleaned condition.

Bust: 38”
Waist: 34”
Hips: 39”
Shoulder: 16”
Sleeve from shoulder: 24.5”
Sleeve from underarm: 17”
Length: 58”
Length (shoulder to waist): 16”
Length (waist to hem): 42”
Condition: Mint