Interesting. It doesn’t look like a private countermark, which would normally be meant to be visible as much as possible. People countermark coins with numbers to reuse them as tokens of some sort, but usually the numbers are much more conspicuous.
The punch also seems to be of high quality unlike most private punches. It looks like it’s a single “10” punch rather than a “1” punch and a “0” punch. So I wonder whether this is an essay punched inside the Mint for detailed examination of the coin and die.
Απόσπασμα: "Leeboy7720"The pictures don't do it justice it's in excellent condition
Ah, that's good to know. It reminds me that I recently got three bronze/copper coins from a seller which all looked cleaned, so I put lower bids than I would otherwise have. I won the three of them and none was actually cleaned.
You would need to find a book or webpage on how mints (and in this case specifically the Royal Mint) proceed for what we now call "quality control". I wouldn't think it's an assay number (to control the metallic composition) but, if an official punch, it might be a number to examine the dies or even possibly whether the striking is done with the right pressure (to avoid weak strikes or "heavy" strikes that would eventually lead to the deterioration of the dies as shown by the "heavy design transfer" type of error).
