The Crown of the Holy Roman Empire also known as the Crown of Charlemagne was made in the 2nd half of the 10th century and now resides in Vienna at the Schatzkammer Museum of Art History. Originally set with various precious gems including the most legendary stone of Medieval Europe the 'Orphanus' Opal as referred to by Albertus Magnus.
"They gleam at each other; the noble stone and the sweet young man, a feast for every princely eye. Those still doubting who embodies the realm may now see on whose head the topstone stands! This stone is the lodestar of all princes." Walter von der Vogelweide, 1198.
Dubbed the 'Stone of wisdom' it was thought to represent the chosen of God and to the Hohenstaufen thinking incorporated all the virtues and symbolised Christ himself. The translucent white opal with an intense red flash glowed in the dark. Around 1350 under the reign of Charles IV the Orphanus disappeared from the front panel of the crown.