Lycurgus Cup: Roman already knew what nanotechnology was..!!!

Working in the field of lasers for producing colors made me explore the history of Lycurgus Cup. One day I was just having a look at the samples and was thinking how nanoparticles (NPs) can alter the color of a specimen when viewed in reflection and transmission (I think you know these terms..!!). My senior then told me to look at the history of Lycurgus Cup.

Lycurgus Cup is one of the greatest achievements of the Roman Era; extraordinary in its workmanship and astonishing in its optical behavior.

Image source: Wikipedia

This cup is dichroic (changes color) in nature. When seen in reflection it turns sea green and in transmission it turn ruby-red in color. Earlier, it was believed by researchers that this material is not glass. Afterwords when curiosity was developed among researchers, this cup was studied in detail by Transmission electron microscopy (TEM) and it was observed that metallic NPs (50-100 nm) were embedded in the glass. Further, X-Ray analysis of the glass showed that these NPs were silver-gold alloy resulting in the dichroism of the cup. Isn't it amazing....!! and we thought that Romans were famous for advance engineering only....!! 

Reference:

[1].  I. Freestone, N. Meeks, M. Sax and C. Higgitt. Gold Bulletin, (2007).