It’s a hell of an illusion.
Promoted from the comment area.
This is Kate Hepburn in a production of Antony and Cleopatra presented by the American Shakespeare Festival. It ran July 12 to July 17, 1960, at the Elizabethan Theatre in Stratford, Connecticut.

Robert Ryan played Marc Antony.


Unless her tits were perfect hexagons I’m going to guess it’s some kind of gem or pattern.
If you zoom in just a bit, you can see a line connecting the “nipple” and the rest of the ornamentation. I think a piece of the design just broke off and we’re seeing the glue or stitching or whatever held it on.
Dunno what we are seeing but by my math Kate was 53 at the time, a bit long in the tooth to be playing Cleo. But I guess on the stage, from the middle of the theater, it might work.
its not see through. its a halter top