HI Jerry and other phillata..., eh, fillate..., eh stamp collectors!
 
I checked with our resident expert, who researched the answer:
 
Reproduction of stamps is kosher if:
   1) the stamp is reproduced in black and white
                      OR
   2) the stamp is reproduced in color in an obviously different size
      than the original.
 
Color reproduction of a stamp in the same size is considered counterfeiting
and is illegal (simialr to making color photocopies of currency).
 
Sincerely,
Aaron Morris