Are These US Scott # Ux21 And Ux21A? Help To Identify Please.

I found these in a collection I bought last year or so. Are these Scott #UX21 and US Scott #UX21a? One does appear to be on bluish paper.
Thanks for any help.
Robert




*** Moved by Staff to a more appropriate forum. ***

Both UX21 and UX21a are printed on bluish paper. UX21 has the legend and the vignette printed in blue; UX21a has the vignette and legend printed in bronze blue. It is difficult to tell bronze blue ink from a scan. The bottom item pictured seems to be suffering from toning which makes telling bronze blue even more difficult.

Held at an oblique angle to a light source, bronze blue will have a reddish tint which is why it is called bronze blue. I have never been successful at this so I compare my UX21 and my UX21a to unk own copies under both an Ott light (daylight) and under UV.

Thanks Jobi01. I will check them under natural sunlight.
Thanks again for the information.
Robert

Well this is interesting. Under regular light bulbs they look the same. In natural sunlight, one looks blue and the other looks more purple. Any ideas what this could be?
thanks again,
Bob

Paper color changes more quickly than stamp color on this issue. Again, the bronze blue refers only to the stamp, not to the paper color. BTW, paper color is obtained by adding die during the paper making process which means that different batches of paper may be somewhat different colors.

If you are reporting that one stamp looks to be blue and the other looks to be purple, the purple looking one may be bronze blue and should be checked by an expert. Both APEX and PF have experts with reference copies. I am not familiar with the other services.

Paper color changes more quickly than stamp color on this issue. Again, the bronze blue refers only to the stamp, not to the paper color. BTW, paper color is obtained by adding die during the paper making process which means that different batches of paper may be somewhat different colors.

If you are reporting that one stamp looks to be blue and the other looks to be purple, the purple looking one may be bronze blue and should be checked by an expert. Both APEX and PF have experts with reference copies. I am not familiar with the other services.

Thanks again for the info. I am going to get a UV light and check them out under that before send for a cert. My original plan was to sell on ebay but I may just keep it as a reference if it does come back as the bronze.
Again thanks for the info and this is a great site with some very knowledgeable and helpful people.
Bob