The leather is sourced from the scottish firm Hewit and Sons. It is made from vegetable tanned young calf skins and presents a deep black colour and a sophisticated mat finish achieved by the special process of drying the skins on glass.
The box is created by assembling pieces of a very hard and dense kind of cardboard, and covering with the black calf. The lining is red suedel.
The covers of the bracelet and the index are made from the same kind of dense, hard board as the box. They are lightly chamfered and covered with the black calf leather. The corners are pleated and very slightly rounded. All the box and leather work is done by hand by Ben Elbel from Elbel Libro, workshop for special binding established in Amsterdam.