A document from the 1500s tells of a search ordered by Emperor Charles IV (crowned at Rome 1355-died 1378) for semiprecious stones in the mountains northwest of Prague. A distinctive type of deep-red jasper, with large inclusions of amethyst and crystal, was found. Thousands of sheets of jasper still decorate the walls of Saint Vitus Cathedral and the chapels at Karlstejn castle built under the emperor's direction. Surviving from the same period are fewer than twenty jasper vessels made for the imperial court, among them this cup and ewer. The remains of the medieval mines are now a protected site within the Czech Republic.