Rayon
Gorgeous vintage dress is made by Blakely Fashions.
 
Pleated wrap style bodice trimmed with three original large, ornate, sparkly buttons with pearls and rhinestones (Pearls are missing a plenty off of these - I kept them on to keep all original)
Dress fastens on the side with a metal zipper and comes with original belt.
Dress is seamed at the waist and flares to a swingy skirt that is slightly more fitted through the hips.
Fabric feels like rayon/crêpe

Dress is in excellent condition. One belt loop has come unstitched on one side and could easily be reattached with a couple quick stitches or snipped off completely. The hem has been shortened and the underneath edge is raw without hem tape… but does not show from the outside.

Overall this is very clean, ready to wear and looks as though it has been stored away carefully all these years. I'm in love with the rich and royal purple plum color… I do not see any fading. 

No tag size is given, however it should fit a modern size extra-large best. Dress is pinned to fit the dress form.

Actual measurements:
Bust: 44-46"
Waist: 36"
Hip: 53"
Skirt length: 23.5"
Back of the neck to waist seam: 16"