This is a super feminine and pretty Ben Zuckerman ensemble, made up of a dress with a sleeveless over-blouse and a jacket in a bright, summery brocade, probably of silk.
This outfit probably dates from the early 1960's. Jacqueline Kennedy was the First Lady at that time and she was very fond of dresses with over-blouses. In the last picture, you can see what the dress looks like without the over-blouse- the top part of the dress was never meant to be seen so was not made of the same, more expensive material as the rest of the outfit.
Photos courtesy of Ebrookana.