I think those are more commonly referred to as "chop marks" and if you could get a better photo of both sides, that would be helpful.
It could be some type of official countermark, BBanker, but I can't see any detail at all in the picture. We either need a clearer image or at least a good description of what it looks like. Bruce
Sorry but I already returned it to it's owner. The punch mark looked exactly like someone had taken a round punch and pounded it half way in to the coin; obviously to make sure it was pure silver. No, definitely not Chinese character of any sort; just a round indention.
