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The Lycurgus Cup is the only intact example we have of what is now called “dichroic glass.” “Di-chroic” means “two-colors” in Greek. The Romans had mastered the art of making one color appear on a goblet when in a certain light and another color appear on the same goblet in another light. The glass goblet known as the Lycurgus Cup appears jade green when lit from the front and appears red when lit from behind the cup.

Until the Lycurgus Cup was acquired by the British Museum in the 1950’s (from the Rothschilds, meaning “red shield”), scientists had not examined it. When they did, they were puzzled by its changing colors. It was not until the 1990’s when broken pieces of the same variegated glass from ancient Rome were examined that they discovered Roman glass-makers were experts in our relatively new field of nanotechnology, technology specializing in very teeny, nano particles.

The Romans had permeated the Lycurgus glass chalice with silver and gold particles that had been ground up so finely they were only 50 nanometers in diameter, less than one thousandth the size of a grain of salt. Roman glassmakers knew that when light hit their glass, something, now called electrons, in the nano fragments of metal would alter the color of the glass. It is sure ancient glassmakers had words for what they did, but those words are lost and we must speak in modern nomenclature.

The glass chalice, known as the Lycurgus Cup, is so-called because it images a myth involving King Lycurgus of Thrace (Balkan Peninsula). A man of violent temper, Lycurgus attacked the god of wine Dionysius and one of his female followers, Ambrosia. Ambrosia called out to Mother Earth who transformed her into a vine. She then coiled herself about the king and held him captive, the scene captured on the Lycurgus Cup. The change from green to red on the vase could symbolize the red blood of Ambrosia or the red wine of the wine god Dionysius. The green could symbolize the ultimate triumph of Ambrosia by being turned into a green vine by Nature that imprisoned the red-wrathful Lycurgus. The vase below shows the moment when Mother Earth has arrived and will save Ambrosia from Lycurgus and his evil behavior.