Ultramarine blue once cost more than gold, so painters saved it for the Virgin Mary

For centuries the richest blue available to European painters came from a single semi-precious stone: lapis lazuli, mined far away in Badakhshan, in present-day Afghanistan. Ground and purified into the pigment ultramarine — literally “beyond the sea” — it was so brilliant and so scarce that it sometimes cost more than gold by weight.

The expense came from both rarity and labor. Crushed lapis alone yields a disappointing gray. The medieval recipe set down by the painter Cennino Cennini turned extraction into a days-long ritual: knead the powder into a stiff dough of pine resin, wax and oil, then work the dough underwater in warm lye, pressing it again and again so only the purest blue particles bled out. The first washings gave the finest, deepest pigment; later ones, a paler, cheaper grade.

Because it was so precious, artists rationed it, and patrons policed it. Commission contracts could specify exactly which grade of ultramarine and how much of it a painter had to use, so the costly color signaled both holiness and the patron’s wealth — above all in the mantle of the Virgin Mary. A century later Vermeer spent on it lavishly, lacing even shadows and underpaint with blue at evident expense.

The monopoly broke almost overnight. In 1824 the French Société d’Encouragement offered a prize for a synthetic equivalent, and in 1828 Jean-Baptiste Guimet won it with “French ultramarine” — chemically much the same blue, but manufacturable for a tiny fraction of the price. The most expensive color in art quietly became one anyone could buy.