I assume that
NGC is much better now than it was when the coin was slabbed but I would
still add pictues of the other
cast fakes with different
weights and the small differences, to lower the chance near 0% that it could be reslabbed as authentic.
There are
still slipping
fakes through
NGC but it is normal no one is perfect.
You can writte Barry Murphy from
NGC he is a member here and on different other boards, not sure if the
auction house will accept it, if you start a topic on cointalk or in facebookgroup where he is very active and ask directly for the
help of him in the
hope that he will possibly feel honored and
help, if he will condemn it, it is like a
NGC condemnation.
Not sure how the
auction house will react if the coin is now condemned by
NGC.
If the
weight of your coin and the slabbed on is identical and no visible differences between
NGC pictures and your coin then they can hardly deny that it is the same coin. (If they want to cheat and say you have exchanged it with a
cast copy).
This is a general problem that many dealers and even
auction houses rely very much to
NGC and their opinion and it than can be difficult to get the
money back for a slabbed
fake.
Some do not even authenticate coins anymore themself and only rely on
NGC, for example smaller dealers, who are not familiar with
ancient coins can now sell
ancient coins because they do not have to authenticate them anymore themself.
For reliable authentication is much knowledge necessary, for correct
attribution often a
search with
acsearch is enough.
I guess in such cases the only way to get the
money back is resubmitting a slabbed
fake to
NGC with information why it is
fake and using the new
NGC condemnation to get the
money back.
It is of course possible to recognize the authentic mother but for reliable results much better pictures or the coin in hand would be required.
I know my limits.
The authentic mother always has the sharpest and best details, some or all details can be recut into the casting mould but this recut details will not be as crisp as on a struck or pressed coin.
The authentic mother has the highest
weight and size, shrinkage in mould of metal when cooling down, exception metal
alloy has been modified for example metal with higher density used,
flan shape modified or if edge cracks will be filled there will be extra metal on the
cast fake not present on the authentic mother.
I would not dare to speculated which is the authentic mother because I am not 100% certain and I do not want risk to declare a
cast fake to the authentic mother and so condemning the real authentic mother.