Gorgeous! Vintage 1970s maxi dress by Adele Simpson. Coral pink silk with a lavender and black abstract print, halter style bodice with deep v in front. Back metal zipper and hidden tiny snaps Halter is not adjustable, fitted with hidden hook/eye clasp. Fully lined in coral silk.  

It is in very good condition. There are a few very faint spots and one mend, all are very well hidden in the drape of the skirt. See the last photo.

Has many other tags but does not have a size tag. The measurements listed below were taken while dress was laying flat and doubled where appropriate. 

Bust - 38 inches around at the level of the top of the back of the dress
Waist - 28 inches
Hips - free
Length from top of strap down side seam to waist - 14 inches
Length from waist to hem - 43 inches
Length from center of V in front to waist - 6 inches