Welcome to the Forum.
To me, everything points to a South American piece.
Such a measurement of the standard, 0.900, in 1780? No, far more likely a 20th century way of expressing it.
Can you make out the middle letter, P.?P. ?
Hi Trey! Thank you!
Yes, my initial thought was also that it is south american - not german, as the seller claimed.
Sadly, this is as good as it gets when it comes to clarity of the hallmark, I suspect there might be 2 letters (stacked) between the P. & P. - the top letter seems to be a ''W''. Could it be two hammers above the letters?
Perhaps Colombian as the other marks in the linked thread, did other countries in latin america use a ''shield''?