A 1766 oil portrait by Jacobus Buys depicting the Dutch art collector and printmaker Cornelis Ploos van Amstel at his desk.

This portrait depicts Cornelis Ploos van Amstel, a Dutch printmaker, collector, and art connoisseur, captured by the painter Jacobus Buys in 1766. The subject is shown seated at a desk, engaged in his professional pursuits. His posture is relaxed, with one hand resting upon a sheet of paper, suggesting a moment of contemplation or active work. He wears a dark coat and a powdered wig, typical of the mid-eighteenth-century Dutch middle class.

The composition employs a restrained palette, dominated by muted olive and brown tones. A green curtain hangs to the left, providing a vertical element that balances the horizontal lines of the desk and the sitter's seated form. The light source is soft, illuminating the face of the sitter while leaving the background in shadow. This technique draws the viewer's attention to the expression of the subject, who looks directly toward the observer with a subtle, knowing smile.

Jacobus Buys was a prolific artist known for his book illustrations and portraits. His work often reflects the intellectual climate of the Netherlands during the late eighteenth century. This painting is a characteristic example of his portraiture, which prioritises clarity and a sense of individual presence over elaborate ornamentation. The desk, the paper, and the simple chair serve as indicators of the sitter's identity as a man of letters and art. The painting remains a record of the social and professional circles in which Ploos van Amstel moved, documenting the appearance of a figure who contributed significantly to the study and preservation of Dutch art history.