100 Francs - type 1862 blue indexes

The "blue indexes" designation refers to the printed serial number and control stamps appearing in blue ink — a deliberate departure from the black-on-white typography used in earlier Banque de France issues, introduced to complicate photographic counterfeiting at a moment when wet-plate collodion photography was becoming dangerously accessible to forgers. The concern was real and well-documented in the bank's internal correspondence of the early 1860s.

Pannemaker was primarily a wood engraver celebrated for reproductive illustration work — his presence on a banknote commission was unusual, reflecting the Banque de France's willingness to draw from fine-art printmaking traditions rather than relying solely on specialist security printers.