Vintage Neiman Marcus shirt jacket

No size tag, but assume a small Flowy fabric feels like silky viscose material but again no tag so I’m not sure. Bought from a vintage dealer in LA. Never wore - perfect condition Smoke free home Measures Top of shoulder to bottom hem 19.5” Sleeve from shoulder seam to lace wrist 23.5” Across bust laying flat 17.5” I think it may have been dyed this beautiful blue color and looks Good worn more like a shaket with a small top underneath. Billow sleeve style with buttons at cuffs - shown in pics