The book covers are entirely richly decorated with plant motifs done in high relief in embossed sheet silver. The decorations composed of curling tendril shaped elements, intricate acanthus shapes and shell and ribbon moulding provide a symmetrical heraldic framing for the armorial bearings. On the front of the cover is a centrally located coat of arms in the shield of which is a cock below three six pointed stars and half moon with face. Above the shield is a nobleman’s crown. The bearings belonged to the Gaos or Gaus family of Rijeka, mentioned in that town for the first time in 1616. On the rear side is a coat of arms in the shield of which are two affronted lions by a crenellated tower with door. This is the shield of the Brajković family of Poljica, mentioned as early as 1420. The object is stamped with the Venetian assay mark of St Mark and the control mark of the Venetian Zecca, but since there is no named mark of a craftsman or workshop, it is possible that it was done by one of the local, Istrian, craftsmen, who were at that time under Venetian jurisdiction and control of precious metals.