Focus on this artwork and explain the Illustrations for comparison.
Wilhelm Valentiner thought the Portrait of a Seated Woman possibly a pendant to the Portrait of a Man in a Wide-Brimmed Hat, but it has since been disattributed. The woman wears a "millstone" ruff.Isabella Coymans is a good example of Hals's "rough" or "loose" style of painting applied to black clothes.
Jan Miense Molenaar (the identity of the sitter is not certain) was painted by Frans Hals at about the same time as the similarly attired and posed Portrait of a Man in a Wide-Brimmed Hat. The face is handled similarly in the two portraits, as is the background. However, Molenaar wears big pleated cuffs, and his cloak is (deliberately) "slashed" to reveal the quality of his white shirt.
The other, later, portrait of a man with a hat by Frans Hals that once also hung at the Herzogliches Museum is now in a private collection. This sitter wears a glove, signalling his wealth.
Jan Miense Molenaar pendant Isabella Coymans ruff Wilhelm Valentiner Frans Hals cuff