Try to find any information about Rosabianca Skira-Venturi, and you will have great difficulty. Except, that she was the author of a series of books, most notably, A Weekend With Leonardo Da Vinci. But Balthus left us with this portrait (1949) of her. An exceptional beauty, in a reserved pose, presented with the notion of less is more. As Robert Brault said, “You don't torture a painting that has already confessed.” Simplicity, here, is balanced with sophistication.
As less information often leads to more interpretation, I still want to know: Who is this woman?