This appears in a current auction listing without any note of the repair. The same coin from an earlier passage in a different sale.
Wow. Yep, same coin, all right. I note the same small scratch at 9:00 near the rim. They toned it up nicely, too.
So what was repaired, the coin or the photo? It would take me about 15 seconds to change photo #2 into photo #1 with Photoshop.
The coin has been repaired - the banker's mark has been filled in. Here's another photo from another venue...
The first image looks like a bad photoshop blur. The one that @pprp posted shows the filling clearer.
I have no idea how a repair such as this could be spotted without knowledge of the prior state of this particular coin. Do we have to scrutinize auction archives on every potential coin on which we plan to bid, not for insight into the desirability and prior sales prices, but to guard against fraud? That makes collecting seem much less fun, to me.
Also, why would you fill in the banker's mark. I understand that a "perfect" coin is more desirable but wouldn't the filling in this case make it less so? The banker's mark is original to the coin and the time period. I'd rather have one with the mark in it showing it was used in trade vs one that had the mark and was filled to be more aesthetically pleasing. Considering these types of coins are way beyond my collecting means, perhaps it just has to do with someone who can afford such a coin and their tastes.
Yes, unfortunately you need to check the history of each coin yourself and not assume that experts-advisors-dealers checked it already. And yes this is very demotivating.
The coin with the banker's stamp sold for 1600 euros. The price without this mark would be 4000-5000 euros. Someone did the repair in an effort to make money.