Although these issues appear to be common, in reality, the genuine ones are very uncommon.
Forgeries of these exist in great numbers and are very well executed.
May 1881 Lithographed - 3 values - The 25 Sh unused is VERY rare, so count on many forgeries
Printed by the Austrian Imperial Printing Works of Vienna
Sept. 1882 Engraved Recess Printed - 3 values
Printed by the Austrian Imperial Printing Works of Vienna
The Sept. 1881 issues have much finer details
The outside border was white in the May issue but colored in the Sept. one.
The background behind the lower numerals is lined instead of a colored fill.
Forgeries
As noted, the forgeries are very well designed and generally the details are clearer. These account for most online offers
The lettering tends to be thicker
2 key points (genuine left, forgery right)
The frames to the right of the rays are well defined and unbroken as in the originals.
The designs below the large numeral are more heavily shaded and lack the shadow in the original.
More 1882 Sc 50-52 forgeries below
In 1882 the 5 Sh was reissued with a change in the color and in the design
In particular, the numeral 5 has no background
Above, genuine left, forgery right
The forgery has the same traits as the 1881 forgery. I do not have enough information to confirm that the high position of the numeral 5 is a common trait.
The 1882 5Sh Sc 53 comes in 2 types
The above value was overprinted in 1885 and 1887 with a new value and the word “OFFICIEL” which indicated that the surcharged stamps were officially authorized
Forgeries of the overprint abound in different positions and inverted. All the fake overprints appear to be on forged stamps so they are easy to spot like the 2 below.
References
Iran Forgeries - Dorn
Iran Scott WW Specialized to 1940
Iranian Philately - Mehrdad Sadri
Persia Forgeries - Bynof
Fournier Album
Persia - Album Weeds
Klaseboer Forgery CD 2 2019
Persiphila articles
Lions of Iran - Mehrdad Sadri -2007
Jay Smith Forgeries
The Stamps of Persia - H. Lewis 1979.
Die Persische Post und de Postwerthzeichen von Persien - Friedrich Schuller
Album Illustrado para Sellos de Correo 1879 - Placido Torres
Special consideration to members of international clubs who provided some images
