Since historical times, noble metal NPs have been used as
decorative pigments for glass [23,24] and ceramic dyeing [25].
The famous Lycurgus Cup (a glass cup of the 4th century AD)
[26] is a striking example of the ancient application of noble metal
NPs to artworks. This cup displays a marvellously green color in reflected
light and a brilliantly red one in transmitted light, which is
due to the presence of gold and silver NPs in the glass matrix
[27–29]. As one of the traditional decorative pigments, silver NPs
provide not only beautiful colors but also an antibacterial characteristic
[30]