The color of the subprint is clearly in green (typically it is brown, such as here), and this feature applies to both the obverse and reverse. Other elements of the print also show a color change. The numbering is clearly lighter orange; the denomination notations are paler, as is the border or the notation BON TOWARDS.
Fracture ridges clearly visible, not pressed, although noticeably lighter.
Most likely color changes caused by the action of what chemical agent?
Color change very striking, but in our opinion most likely unnatural, induced secondarily.
