Somewhere in northeastern Afghanistan, about six thousand years ago, someone dug up a stone that was the wrong colour. Rocks are not supposed to be that blue. They're supposed to be grey, brown, dull. This one glowed like a trapped piece of sky, and somebody thought: I wonder what happens if I grind that up.
What happened was ultramarine – the most expensive colour in the medieval world, and for a few centuries, the most politically loaded decision a painter could make.
Lapis lazuli, the stone in question, came almost exclusively from the Sar-e-Sang mines in what is now Afghanistan. To get from there to a painter's workshop in Florence or Siena, it crossed the entire known trading world: through Persia, through Venice, through a string of merchants each adding their cut. By the time it arrived as a dry pigment it cost more, weight for weight, than gold. Artists and their patrons both knew this. They acted accordingly.
The result was a peculiar kind of art direction that had nothing to do with aesthetics. Contracts between painters and their clients – actual written, witnessed contracts, many of which survive – specified not just the subject of a painting but exactly which figures were allowed to be painted in ultramarine. A patron paying for an altarpiece was effectively buying a hierarchy. The Virgin Mary, almost without exception, got the blue. She had earned it, theologically speaking, and whoever commissioned the painting was demonstrating, in the most tangible way possible, that they understood her worth. Lesser saints might get a blue robe, but it would be azurite – a cheaper, greener substitute that tended to turn muddy over time. Knowing this, you can walk into almost any medieval or early Renaissance church and read the pigment choices like a cost sheet. Blue on the Madonna? Real money. Greenish blue on the figure in the corner? Budget option.
For more on the extraordinary story of this colour and the trade routes that made it possible, The Colour That Bankrupt Painters and Blessed the Virgin goes into the full, strange history.
Painters themselves were sometimes caught in an impossible position. If a patron specified ultramarine but then ran short of funds, the artist might end up covering the difference himself. Which is exactly as ruinous as it sounds. Some painters hoarded their supply, rationing it across a commission so carefully that you can almost trace the anxiety in the brushwork – a little more diluted here, a background done in something cheaper, the precious stuff saved for the face. It is, in its way, the most human thing about these enormous solemn paintings: somewhere behind the gold leaf and the angels is a man doing sums.
Synthetic ultramarine arrived in the 1820s, affordable and chemically identical in colour, and within a generation the Virgin's robes stopped meaning what they used to. A colour that had signalled devotion, wealth and the correct ordering of the universe became just another option in the paint box. Which is perhaps the strangest thing pigment has ever done – not just change what we see, but change what it means to look.
