This totally glam dress is from the 60's. Lots of prong set rhinestones of various sizes decorates the yoke of the front of the dress and the straps in the back. Beautiful style. There is faint persperation stains under the arms. Very hard to see. I believe this would best fit a S but please check the measurements provided and compare for a proper fit.
Measurements

Armpit-armpit 34"
Waist 33"
Hip 38"
Length from top of shoulder to hem 35"

This item is sold from an excellent, highly rated vintage boutique in Westfield, Massachusetts.