Bhonsla rajas of nagpur, katak mint, in the name of mughal emperor Ahmed Shah bahadur. 1754-84 Maratha empire. The coin is interesting in of itself, but what caught my eye is the christian cross punchmark on the obverse. My guess is that it was done by some christian minority community in Nagpur. During these times, the british had sent christian missionaries to India to spread christianity and gain converts. Notable among these converts were the Marathi christians of the Maharashtra state where nagpur is also situated. Significant progress was made when the bible was translated into Marathi language by a baptist missionary. Someone from the marathi christian community or maybe a missionary might have resorted to stamping the cross on the local coinage as a way of spreading the idea of christianity. This is just my speculation on the story behind this coin. Would love to know what you guys think.
It's more likely that this is some sort of "bankers mark." Basically, if there's an unusual coin and the "banker" (or shopkeeper, or whoever) didn't recognize it or didn't trust the silver, they would mark it to see what was underneath. Many counterfeits were made from a lead or copper core and just silver plated - making a deep mark like this would show if it was silver plated or solid. Marks come in basically every shape, letter, character, or symbol imagineable.
I agree schroff marks can be a possibility, but in all the mughal rupees I have seen, the silver test mark is either a cut or a circular dent on the flan. I havent seen such specific shapes, which begs the question of underlying meaning.
It may be hard to prove, but based on the history you provided, it certainly is a possibility to consider IMO. Hopefully, you'll come across additional examples that could support your theory.
