I tried to determine the correct catalog number for the various NBN / CBN / ABN stamps myself. To test how well I did, I sent two of them off for authentication/identification. I chose the vermillion 2¢ stamp and the carmine 90¢ stamp. When they came back, one was right and one was wrong. I could have flipped a coin and done that well! I was then obliged to send off 8 more for identification. The end result was 7 identified correctly and 3 mis-identified. Clearly, I am no good at differentiating banknote paper types!

NOTE: I did send off the 30¢ issue even though it was very unlikely that it was a $275 stamp misidentified as an $80 stamp, but why not take a gamble! I did not send off #153 (CV $200) on the off chance it was really #164 (CV $357,500). That's not taking a gamble. That's more like throwing your money away. Might as well buy lottery tickets if I'm going to throw money away!