Roman nanotechnology in art

[mediaevalist]

I've touched upon this before with an article on the nanotubes present in Damascus steel, but that wasn't just a happy accident. The Romans indeed knew what they were doing:

This 1,600-Year-Old Goblet Shows that the Romans Were Nanotechnology Pioneers

The glass chalice, known as the Lycurgus Cup because it bears a scene involving King Lycurgus of Thrace, appears jade green when lit from the front but blood-red when lit from behind—a property that puzzled scientists for decades after the museum acquired the cup in the 1950s. The mystery wasn’t solved until 1990, when researchers in England scrutinized broken fragments under a microscope and discovered that the Roman artisans were nanotechnology pioneers: They’d impregnated the glass with particles of silver and gold, ground down until they were as small as 50 nanometers in diameter, less than one-thousandth the size of a grain of table salt. The exact mixture of the precious metals suggests the Romans knew what they were doing—“an amazing feat,” says one of the researchers, archaeologist Ian Freestone of University College London.

The technique wasn't completely forgotten: red stained glass was very expensive to craft due to the requirement of crushed gold mixed into it.