Inherited Coin - Lydian?

Has anyone noticed the impressed "18" near the bottom edge on the obverse side?

(I don't think the Lydians used the number characters that we use today )

Yesterday I saw the description below for a similar coin.

"ANCIENT COINS. Greek. Caria, Knidos (c.465-449 BC), Silver Drachm, forepart of a roaring lion right, its jaws gaping and tongue protruding, rev head of Aphrodite right, within an incuse square, 6.12g, 8h (Cahn 85 (V 39 / R 54); Jameson 1534 (these dies); BMC 18-19 (these dies)). Attractive transitional style, cabinet tone, very fine to good very fine."

Where can I find additional information about the different die classifications, e.g., Cahn, etc?

These "collector punches" are always on the field or the edge of the coin, clear from the images or portraits while the bank punches are usually on the hight relief of the coin to test the silver of the coin...
The powerful family of Gonzaga in Milano (Italy) used a winged eagle to mark the coins of their collection...
this was a very popular thing at the renaissance period...

There are two things about the OP coin that bother me a bit:
1. The mashed appearance of many of the longer engraved lines on both sides and
2. At 5 grams the weight is too light by 17% at least. Most of the early examples at acsearch came in a 6-6.4 grams
CNG had a later version of this, with an inscription below bust of Aphrodite, that weighed 3.56 g but everything else was over 6.

I would have the metal checked before I accepted it as original. The mushyness of the lines hints at a reproduction.
The guess about the origin of the "1B" punched marker is just a guess, and not the only possible source/meaning for such a thing. To me it looks like it could be a ligatured "NB."

The ancients were generally pretty consistent about coin weights in silver, but these varied over time, sometimes up, sometimes down. However, for a minting in the late 5th century BC, 5 grams would be suspect for this. More study would be required to pin it down for sure.






Even if we could agree on that characters those are, I doubt that we can determine what they meant or why they were applied. We don't even know what language was used. Greek had an upper case N and B, as did Latin, and many languages since then (but not Cyrillic). The letters could be initials for a persons name, or a company, or a warning phrase, or ? If numbers, the use of Arabic origin numerals takes it out of the hands of the ancients for sure. Numbering for reference to a list, inventory, acquisition log, and so on could have been added to distinguish modern product from ancient original, or who knows what all else.

The surest thing we can say is that we don't know what those characters mean.