Identification of the 6¢ large banknote
Step 2 - Look at the border on the side
About the addition of the line of shading
Unlike the previous 6¢ stamps which had simpler shading, #208 featured additional lines of shading and deeper engraving in the frame and border to distinguish it from the earlier, less-defined versions. #208 was printed on soft porous paper (most earlier versions used hard paper), which required new, stronger plates to be produced, allowing the engravers to alter the border lines during this process.