Khan Academy: The Holy Thorn Reliquary of Jean, Duc De Berry

This reliquary was made to house a relic of the Crown of Thorns, the wreath of thorns placed on the head of Jesus Christ at his crucifixion. The thorn is displayed behind a crystal window and is identified by a Latin inscription: Ista est una spinea corone / Domine nostri ihesu cristi ("This is a thorn from the crown of Our Lord Jesus Christ").