A woman with pale, luminous skin and softly flushed cheeks faces slightly to her left, her gaze directed forward with a gentle, composed expression. Her chestnut hair is parted in the center and styled back from the face, with a delicate lace-edged cap just visible at the back of her head. A single gold ornament is set into her hair on the viewer’s right, catching the light against the dark curls.

She wears an elaborate, starched millstone ruff, its pleats radiating outward in crisp, white layers edged with intricate lace, casting subtle shadows on her neck and shoulders. A double strand of pearls encircles her neck, and a gold chain with multiple strands drapes in a loop over her black gown, adding a note of richness to the restrained palette. The bodice of her gown is rendered in deep black, with the texture of the fabric suggested by soft, controlled brushwork, and the gold chain stands out vividly against the dark surface.

Light enters from the left, illuminating the sitter’s face and collar, while the background remains a smooth, neutral grey, subtly modeled to suggest depth. The composition is oval, focusing tightly on the upper body and head, with the hands not visible, centering attention on the sitter’s features and costume. Fine brushwork is evident in the rendering of lace and pearls, while the face is modeled with delicate transitions of light and shadow, creating a lifelike presence.

The signature 'Rembrandt f. 1635' appears on the left above the sitter’s shoulder, confirming the artist and date. Portrait of Petronella Buys was painted by Rembrandt in 1635, as noted by the artist’s signature and the date on the panel.