Were ancient romans nanotechnology pioneers? Amazing Lycurgus Cup

The Lycurgus Cup, as it is known due to its depiction of a scene involving King Lycurgus of Thrace, is a 1,600-year-old jade green Roman chalice. Like many others.

But when you put a source of the light inside it it magically changes colour. It appears jade green when lit from the front but blood-red when lit from behind or inside.

It baffled scientists ever since the glass chalice was acquired by the British Museum in the 1950s.

Then in the 1990s they discovered tiny particles of silver and gold in the cup's glass. When hit with light, electrons belonging to the metal flecks vibrate in ways that alter the color depending on the observer’s position.

But how did the romans dissolve silver and gold into the glass? 

Researchers speculate that the Romans simply ground the metal particles until it would take a thousand of them to match the size of single sand grain, then mixed them in with the hot liquid glass. But that wasn't the end of the story: the Romans created a goblet such as the Lycurgus Cup, by carving it from a single block. That means they also understood that different thicknesses of the glass would exhibit different coloring as well. That's a nanotechnology

The artisanship this required boggles the mind. The glass makers could not have added such minute amounts of gold and silver just to the glass the cup was going to made out of. These particles are 50 nanometers wide, less than one-thousandth the size of a grain of table salt.. You can’t even see them with an optical microscope, never mind the human eyeball; you need a transmission electron microscope at least. New research has suggested that the cup also changes colors when liquid is poured into it (although the researchers did not do so as it might have caused damage).

The cup may have been used in Bacchic rituals which were still in practice in fourth century Rome. In addition to the story the cup tells, the color shift from green to red parallels the maturation of the grape. Historians have also posited that it might be a political reference to Constantine’s defeat of Licinius in 324 A.D. It was certainly a specific commission and a hugely expensive one at that, with everything from glass color to theme to decoration being top of the line and one of a kind. The cup is also a very rare example of a complete Roman cage-cup, or diatretum, where the glass has been painstakingly cut and ground back to leave only a decorative "cage" at the original surface-level. Many parts of the cage have been completely undercut. The cup was made probably in Alexandria or Rome in about 290-325 AD, and measures 16.5 x 13.2 cm.