The fan in Agatha Bas's hand projects beyond the edge of a painted frame, as if held out to the viewer, and that is the central trick of this 1641 portrait. As the Royal Collection explains, Rembrandt set the sitter inside a painted ebony frame, a new device for him, and rested her hand on it. The canvas was later cut down, which weakened the effect.

Beside the signature Rembrandt f. 1641 the artist recorded her age, AE 29. Agatha Bas (1611–1658) was the wife of the wool merchant Nicolaes van Bambeeck; both portraits are dated 1641, three years after the marriage, but today he hangs in the Musées royaux des Beaux-Arts in Brussels and she in London. She wears a black gown over a stomacher of gold-flowered silk, a pale pink skirt and several strands of pearls.

Lord Yarmouth bought the portrait for George IV in 1819. Struck in the United States in 1972–1976 in .925 sterling silver, the medal renders her likeness in relief.