Hello everyone,
I've decided to open a post where everything Japanese can be discussed. We can share our common knowledge of Japanese stamps, show our collection and ask questions.
I would also like to add any valuable identification of fakes here.
Also, I have access to Japanese resources and can help (with the limitation of my abilities) with identification and translation.
For this first post, I will be posting two example of clear forgeries.
The first: Koban, Five Sen, with obvious cancellation forgery, as exposed by the red circles on the picture. It is my understanding and after researching a bit via specialised sites that one of the many ways to identify Koban forgeries, and perhaps one of the most obvious, is to look for a forged postmark or cancellation. In the example below, the cancellation is incomplete, it stops at the edge of the stamp leaving un-inked or white areas where the cancel should normally expand to the medium on which the stamp was applied.
These cases of forgeries are most often met on the infamous "souvenir sheets", but these sheets being well known now, unscrupulous dealers, or unaware collectors will sometimes mix genuine stamps and forgeries altogether.
To note as well the ink of the forged postmark is slightly off when looked at carefully. While most Japanese black cancels have a deep black dye, on this here forgery the ink has a silvery and uneven dye. (similar to the reflection of strong pencil strokes)

The second example: Eight Sen. Here the proofs of forgery are in two forms. First to the left, and while less obvious than on the previous example, we meet again the faulty cancel mark and the silvery ink. Second, moving on to the left and right of the center in the two yellow circles we can identify two Kanji, meaning "
Sanko" or facsimile or imitation. (cf:
https://isjp.org/introduction/)
It appears that a wide variety of early Japanese classic stamps bear these kanji somewhat hidden on the stamp, as the IJSP better explains in its forgery articles.

More will come on forgeries as I have recently encountered nonperf forgeries and would like to share with you on that matter.
As this is my first post, do let me know in PM if I have made any mistakes in editing or anything else. Thank you in advance.