The Sperati counterfeit is very deceptive and sometimes even has a fake cancel, making it more difficult to determine. I recently purchased a Sperati Countfeit #5 on Ebay. The seller did not know that it was not genuine.
The back side of the "E" in POSTAGE is not smooth but has a jagged break in the letter.
The upper right "1" in the 10 is malformed, looks almost like a 3 under magnification.
The upper right star has a color dot in it
There is a colorless area at the base of the 10 at lower left.
Many genuine copies of this stamp are very difficult to identify against the Sperati counterfeit, because their are many variations in color of ink, cancels obliterate the differences in some cases and the quality of printing on the originals is not consistent. That is what makes the Sperati so dangerous, for CSA collectors.
