Saturday, April 02, 2016

The Lycurgus Cup Changes Colour When Held Up To Light

This cup, made in Rome in the 4th century AD, is the only complete example of a very special type of glass, known as dichroic, which changes colour when held up to the light. The opaque green cup turns to a glowing translucent red when light is shone through it. The glass contains tiny amounts of colloidal gold and silver (nanoparticles), which give it these unusual optical properties.

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