Continental Bank Note Company simply reused the National Bank Note design when it created the 12-cent Clay issue, and therefore the small, secret mark applied by CBNCo to the original printing plate can be cited as its sole artistic contribution to the entire 1873 Issue. The mark was etched out of the ‘2’ at the bottom center (under the portrait), making the two curls of the number appear more crescent-shaped. The difference between this ‘2’ and the even, fully rounded shape in the National Bank Note stamp is very noticeable when directly compared.
The 12-cent Continental Bank Note Company stamp, in combination with a 1-cent stamp, could have paid the registered fee and first-class mail rate or an unusual quadruple first-class rate. This stamp was also used in combination with many other stamps to pay larger foreign destination rates. Approximately 2,915,000 stamps of this issue were printed by Continental Bank Note Company.