Originally posted in The Paris Review.

Full title: The Virgin in Prayer
Artist: Sassoferrato
Date made: 1640-50
Copyright © The National Gallery, London

Michelangelo couldn’t afford ultramarine. His painting The Entombment, the story goes, was left unfinished as the result of his failure to procure the prized pigment. Rafael reserved ultramarine for his final coat, preferring for his base layers a common azurite; Vermeer was less parsimonious in his application and proceeded to mire his family in debt. Ultramarine: the quality of the shade is embodied in its name. This is the superlative blue, the end-all blue, the blue to which all other hues quietly aspire. The name means “beyond the sea”—a dreamy ode to its distant origins, as romantic as it is imprecise.

Derived from the lapis lazuli stone, the pigment was considered more precious than gold. For centuries, the lone source of ultramarine was an arid strip…