The most lavish medieval books were bound in covers set with enamels, jewels, and ivory carvings.
 Book Cover Plaque: Christ in Majesty, ca. 1185–1210 French
Gilded copper and champlevé enamel 
Source: Heilbrunn Timeline of Art History | The Metropolitan Museum of Art

The most lavish medieval books were bound in covers set with enamels, jewels, and ivory carvings.

Book Cover Plaque: Christ in Majesty, ca. 1185–1210 French

Gilded copper and champlevé enamel

Source: Heilbrunn Timeline of Art History | The Metropolitan Museum of Art