This is a nice waisted  sleeveless dress that belonged to my Aunt who lived in NYC and shopped in exclusive stores. From the size  that she wore I am assuming it was from the  50s or 60s.. It looks like she never wore it as the tag is still on. It is made of 55% rayon and 45 % silk as stated on the tag. (see photos) It was originally 46 dollars and put on sale for 23 dollars.
It is marked as Lot Size 16 but seems considerable smaller compared to today's 16. I am usually a size 12 and it fit but I was unable to fully zip the back. There are darts by bustline.

It is in good condition with no visible stains or tears.

I am not a clothing seller so don't know exactly how vintage clothes translate to current sizes. Below are the approximate measurements:

All measurements were taken from the front from one front side to the other,

Shoulder to Shoulder 16 in
Armpit to armpit 18 1/2
Waist 14 1/2
Length from top to hen 42 in
Zipper 23 in
Waist to bottom 26 inch

Pictures Below, both outside and inside.