Quote:
Letters are straight and stamp border too.
The reason it is straight in some areas and not straight in other areas has to do with the alignment/registration of the color dots.
6 different color plates were used to produce this stamp. When some color align well, you will see nice clean edges except under extremely high magnifications. When some colors are misregistered, then you will see the jagged edges (in the bottom letters). It all happens to depend on which colors form the letter boundary and which ones are misregistered.
You are very visually perceptive! Not many collectors like that around anymore.