The Lycurgus Cup is a Roman cage glass, or diatretum, made from dichroic glass. This means the attributes of the glass permit it to vary colors based from where direction light is shown through.
Produced at some point in the Fourth Century, the cup shows a color-changing feature which makes its glass have various colors, based on the source of light. If lighted from behind, the cup becomes reddish and greenish when lit up from the front side.
Approximately six inches tall and five inches in diameter, the Lycurgus Cup is extraordinary. It is not the only finished Roman item crafted from dichroic glass to outlive, but also it is the sole extant dichroic glass to possess such overwhelming tone switch, from opaque green to an intense transparent dark red. It’s furthermore the only diatretum, or reticulated glass — a cup ornamented by crushing away portions of solid glass making an ornamental relief attached to the outer casing of the glass.
The glass describes the ancient Greek story of the Thracian King Lycurgus. Lycurgus got an awful demise from Dionysus who cursed him because banning his faith and putting his devotees to jail. There are various variations of this myth, however the mention seen on the glass ( Lycurgus caught in wine vines) is not a common one. Still, we have a satyr and a figure thought to be Dionysus.
The glass might have been utilized in Bacchic rituals that were still in use in fourth century. Besides the story the glass shows, the color change from green to red evokes the growth of the grape. Historians also have imagined that it could be a political mention of Constantine’s loss of Licinius in 324 A.D. It was definitely a particular order as well as a extremely costly one as well.
By coincidence, the Historia Augusta reports the gift of two dichroic glasses from Hadrian to his brother-in-law Servianus through a record. Possibly, this might have been one of these. Vopiscus detailed some dichroic glasses in “The Lives of Firmus, Saturninus, Proculus and Bonosus” from the Historia Augusta. He refers to correspondence supposedly composed by Hadrian to his brother-in-law Servianus:
“I am giving you over some glasses, shifting colors, given to me by the priest of a temple, especially to you and my sister. I would like you to utilize them on feast-days”.
The British Museum obtained the glass in 1950′s, however it was not before the 1990′s that the properties were understood. Experts examined pieces of the glass until finally they found that the Romans happened to be nanotechnology innovators. The glass effect of the Lycurgus Cup was attained by putting some glass with blended silver and gold particles.
Reported by the Smithsonian Magazine, once struck with light, electrons from the metallic flecks oscillate in many ways which affect the colors depending on the observer’s angle. The size of these particles of silver and gold are merely around 60 nanometers (no more than one-thousandth the size of a grain of sand) and needed a electron microscope to be noticed. Therefore, it is very unlikely that Roman artisans created these tiny silver-gold blend dirt particles for the dimensions of glass; so, these grains need to have been included in large volumes to even larger quantities of glass-melts. Thus, there might have been several other dichroic glass products made of the same glass-melt as the Lycurgus Cup.
The glass-maker put in 330 portions per million of silver and 40 ppm of gold, but simply incorporating small amounts of metals into the glass would not produce a dichroic reaction. The crucial phase occurs when the silver and gold change into crystals named colloids that change state in the glass creating a metal. These types of crystals disperse light relatively uniformly. In carried light, the crystals spread blue better than red, so making the cup look reddish to the viewer.
After the glass manufacturers completed making the cup, then some other set of geniuses arrived: the glass carvers. They cut away at the surface of the thick-walled blanks by using small rotary wheels capped with an abrasive mixture prepared by mixing sand and quartz, with water or oil. They completed the high quality features with abrasives. The result of this extreme work is a high sculpture linked to the surface of the glass with thin connections. On the Lycurgus cup, these connections are grape vines along with other figural components.