RB2A Or RB2B Green Paper?

ive done a little looking online but cant tell and I have nothing to compare it to but an RB1a which looks lighter front and back. The scans do them no favors either - they look lighter.... Pointers and confirm appreciated. Thank you.

Appears violet. The best way to tell if one does not have comparison examples is to put the stamp under UV. Violet and intermediate papers (a paper which might look green to the naked eye alone, but will instantly appear violet when placed next to a true green paper) will show up as violet under UV; only true green paper will appear green. Also, although the catalog says both stamps have black vignettes, green paper stamps actually have sepia vignettes, which appear brownish. Also there tends to be some color seepage of the vignette on the reverse of green paper stamps.

For reference.

Ok, will do. thank you for the advice. short or long wave?

So I did long wavelength and the 1¢ definitely looks violet / purplish and the 2¢ does not seem to change color. im looking primarily at the center image area.

Look at the reverse under UV.

ahhh. ok, the violet is definitely violet - the1¢, does change to violet. While the 2¢ does not change like the other - but - it does seem somewhat , though very lightly, purplish. going with RB2a.

That you for another lesson.