Why Is The Middle Stamp A Lot Different In Color?

The middle I know is from a different year but when I look up the year I can't find one this color

Maybe because its a completely different stamp

There are frequently color variations in stamps, Often not well explained the catalog. On occasion, stamp could also have been somehow chemically altered, such as exposed to bleach. Determining color of a stamp is often very difficult .

This does not have anything to do with variations. It is difficult to tell from the small picture, but there are at least two different stamps there! Dynamode is correct,

Peter

Agree with FredC. The middle stamp had many printings over its lifetime; the design was used for more than one issue. If you are looking at a Scott catalog volume 1 or something similar, the listings are not complete for all colors. A Scott US specialized full volume might give you a better match but again do not have a complete listing, nor are the variant colors necessarily rare. From what we can see, this is in a range of common colors/shades.

Again per FredC, time and imperfect storage can affect color.

Try Scott #248...