The Lycurgus Cup is one of the best preserved Roman cage cups.
Initially, experts werent sure whether the cup was made of glass, or was a gemstone.
It wasnt until 1990, that researchers figured out how the color changers were brought about.
But thats not the end of the story.
Simply adding ground-up gold and silver to glass would not produce these unique optical properties.
For that the gold and silver particles need to form minute submicroscopic crystals or colloids.
It is these colloids that give rise to the light scattering phenomena that result in dichroic effects.
For example, opaque red and brown glasses were produced by the addition of copper.
The inability to control the coloring process explains why the technology never developed beyond the fourth century AD.
There are a few other examples of nanotechnology in ancient history.
These swords were produced in the Middle East between the 3rd and 17th century.
The presence of nanoparticles in these materials, however, doesnt mean that the ancient people knew about nanotechnology.
They did not know that they were working on the nanoscale," he says.
Sources:Phys.org/Wikipedia/Smithsonian/Ian Freestone, Nigel Meeks, et al/Guardian
