I read your title as what the hell too!!
I have been spending a lot of time recently with my
Chinese and
Vietnamese cash coins, which include a lot of
contemporary counterfeits, unofficial issues, etc. When it
comes to
Vietnamese cash in particular, 3rd or even 4th generation casts (casts of casts of casts) are common and of course even the original issue coins were cast.
The point is I have recently been looking at hundreds of
cast coins and it helps to exercise the eye when it
comes to trying to spot casts of struck coins.
Coin #1 just screams cast to me. The muddiness of the
reverse lettering in particular. This is subtly different from natural wear. The blob where the
exergue should be is an even better clue as it is clearly not wear. It is a blob formed from
poor casting - perhaps a poorly formed "negative" in a sand mold.
Coin #2 is better. The horizontal line at the top of the
reverse could at first glance be taken for a die
crack. However the
mint mark is
still blobby enough to set off alarm bells and cause the close examination which would highlight more issues re lettering.
Coin #3 is even better in that it appears to be in poorer condition and the lettering looks more worn than the result of
poor casting. It might have received post-casting abrasion to wear it down. I would have bought this coin if it was
cheap. But knowing it was
rare, and being the suspicious
type, I would look further and be concerned about a blob in the
mint mark. While the whole
mint mark is no longer a single blob (maybe it was
tooled) there is
still metal present where there shouldn't be - between
mint mark letters. This metal does not look like corrosion or adhesion product but looks like what it is - a casting flaw.
Coin #4 is very convincing. If not original then it is a high
quality cast made by someone with skill. Concerning - and only an issue if checked very carefully before a big purchase - is the small dot/blob behind the
head and the slight mess at the
modius on
head of right hand figure / adjacent letter. These would have to be a) casting flaws, b) die damage, or c) an early adhesion product that then gained the same
patina as the rest of the coin. I agree that a true thin hard black
patina may be very difficult or impossible to create, but you can't tell from a photo that it is such a true har
patina - could be a
good paint job till you get it in hand.
Coin #5 is also very convincing, at least as a photo. The thick yellow-green
patina is clever if this is a fake as it hides casting muddiness. Likewise the deep scratches could hide casting flaws. When i blow the photo up though I do see indications of
porosity - lots of possible tiny casting bubbles. However, the
poor condition and remaining
patina might make you think it received harsh treatment - either in the ground or at the
hands of
man - and dismiss the concerns. Would likely need this in hand to be sure.
Shawn