I hope you mean this as a joke. It certainly was not ringflash, not was it solarized.
I own a Weston nude of "Charis on the Dunes" which exhibits the same qualities, as do several of his others. When the axis of the lens is very close to the axis of the light source, the light will wrap around a curved surface and produce the dark outline. Try it with an egg, as demonstrated by Ansel.