Portrait of a man with ring and touchstone, probably Bartholomeus Jansz van Assendelft (1585-1658)

The small black slab under his hand is a touchstone, and it tells you his trade. A goldsmith or an assayer drew a piece of gold across a stone like this, leaving a thin bright streak, then laid it beside streaks from test needles of known purity and compared the colours. The ring he holds up toward us is the kind of object that went through that test. The sitter is probably Bartholomeus van Assendelft, a goldsmith from Leiden, and Valckert put his own signature and the date, 1617, on the stone itself. Against the black clothes and the dark wall stands the great white ruff, its folds laid on so thickly that the paint stands up from the panel. The portrait stayed with the Assendelft family into the 19th century, later belonged to the Hague society painter Antoon van Welie, and was bought from his estate in 1957.