Grisaille is the painter's discipline of modeling an entire world in cool neutral grays — no color, only value — to make paint imitate carved stone. Jan van Eyck made it canonical on the exterior shutters of the Ghent Altarpiece, where saints stand as if hewn from stone.

This design system distills that achromatic relief tradition: a mid stone-gray ground, a full value ladder from deep shadow to white highlight, and the signature cool Payne's-gray midtone. Volume comes from chiaroscuro, never from hue.