1960s YSL Silk Blouse

A vintage (with tags) 100% silk blouse by Yves Saint Laurent Rive Gauche. The blouse features a high collar, gathered neckline, gathered shoulder seams, button sleeve cuffs and a back neck button closure and keyhole opening. Size 34 FR. approximate measurements laying flat: 18" pit to pit, 24" shoulder seam to hem. Both the YSL tag and the original Bloomingdale’s tag still attached suggest to me this is from the late 1960s, though it’s possible it’s very early 1970s. No rips, snags, or stains, but is missing a button on one sleeve (see photos). If I were keeping this, and not as an archival piece, I would have a tailor use the button at the keyhole closure at back to replace the missing button at the sleeve and add a decorative button at the back. 1960s Yves Saint Laurent pieces are very difficult to come by, even more so in this condition.