Alwin, Hats off You found an example very very similar. Is such similarity normal? May I know where you found that coin? Any provenance? I know some fakes casts or transfer die fakes can produce a very similar coins.
As to why the lump makes me doubtful , I think some cast coins could demonstrate a lump due to mold imperfections and faults it is same thing that causes extra metal pearls on some cast coins.
Dave
Your first reason to suspect it is that it might have been from transfer dies and the second reason is that it might have been cast? That makes no sense at all. If you have a genuine concern, it should be one of the other. If you have both, your ability to authenticate is not well developed enough and you should depend on reputable and expert dealers, or 3rd party authentication. If you find this insulting, don't. I can't play golf well and if someone tells me so, it isn't an insult, just the truth. If I really want to play golf well, I should expect it will take a lot of practice and time. Experts who can accurately authenticate
ancient coins have years of experience examining tens of thousands of coins.
Genuine coins are often similar. Similarity is not an authentication issue unless one of the following applies: (1) The similarity is to a known
fake. (2) The similarity indicates they were cast from the same mold. (3) The similarity indicates one was used to create a mold for the other. (4) Both coins share features that are not from genuine dies. They are from the same
flan flaw(s), strike flaw(s), or post strike flaw(s) that were transferred to the mold or transfer dies used to make the
fake. Knowing the difference between flaws that come from the same genuine dies and problem flaws that come from the same mold or transfer die and indicate a
fake is not always easy.
The "lump" is not at all similar to a pearl. A pearl results from an air bubble in the mold. A pearl is spherical.