DVF Initial and Tiny Dot Print Vintage Blouse - label/tag at back of neck is cut out, but I assume this is Diane von Furstenberg (see closeup of sliver of tag at back neck)
Material is whisper weight, thin and smooth and fairly sheer like polyester or nylon. No fabric tags. I believe the tiny dots are black.
No size tag, may fit modern S or M. Compare measurements to a top you own. 19. 5" underarm to underarm / Shoulders 16"/ 25" long/ Sleeve 23".
Flaws: one stitch line around underarm was open so I hand sewed with small stitches to repair. bottom button was missing so I replaced with small clear button. horizontal and faint vertical snag on front blouse, I did closeup photo of area, not an obvious flaw.

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