While building my Chile collection, I came across these two stamps. They are both Scott # 91's. The color listed in Scott is "Ultra", which I assume is the first stamp shown. The second stamp is also a Scott #91 but with a drastically different color. It is no longer "Ultra" blue, but a very light blue. There is still some remnants of Ultra blue in the letters and numbers though. My first thought is that it is just faded, but the black ink in the center of the stamp looks like the original so maybe hasn't faded much. Do different colors, like blue, fade faster than other colors? Because the colors are different (blue vs black), I'm assuming the chemical makeup of the colors is different as well. The only other option I can think of is that the printer was maybe running out of blue ink for the second stamp? What do you think?