Figure 1
Examination of a used envelope or cover.
Figure 2
Comparison of the two Maltese Crosses.
Figure 3
If the cancellation of the stamps was made at the same time, the spectra from each will be the same, assuming that the person using the obliterator used the same ink. However from the spectra in Figure 3, it can be seen that the Maltese Cross traces on the Mulready cover and stamp are different. Hence, indicating fraudulent manipulation.
Figure 4
Using a video spectral comparator. The colour of the Maltese Cross was changed from black to red to aid postal authorities to check that the stamp had been used.
Figure 5
The item under investigation is compared with reference material.