It probably remained at Waulsort until French Revolutionary troops looted the abbey in the 1790s. Perhaps it was they who threw the crystal - clearly made for a hateful king - into the nearby River Meuse. When it was found it was cracked, but otherwise completely undamaged, because rock crystal is astonishingly tough. It is very hard and cannot be chiselled, but must be ground instead with abrasive powders. The whole thing would have taken an immense amount of time and great skill to work, which is why these crystals were such luxury objects. We don't know what the original purpose of our Susannah Crystal was, possibly it was an offering to a shrine, but it was in every sense an object fit for a king.

By the time the crystal was made, Charlemagne's empire had broken down, and the whole of north-west Europe was divided between three members of his squabbling and profoundly dysfunctional family. The squabbles ultimately resulted in the empire being divided into three parts: an eastern kingdom that would later become Germany, a western one that would become France, and Lothair's Middle Kingdom, called Lotharingia, which ran from modern Belgium down through Provence into Italy. But Lothair's Middle Kingdom was always the weakest of the three, forever threatened by wicked uncles on either side. Lotharingia needed to be able to defend itself. It needed a strong king. Here's Professor Rosamund McKitterick from Cambridge University.