3 questions about Korean cash coins

I have recently tried to identify a collection of 88 old Korean coins, with some success, thanks to the very useful primaltek.com site. Here are 3 questions that are still unanswered:

1. Should I rely on the size of the coins to give them a face value? In other words, do all "1 mun" coins have a size of 23-25mm, and all "2 mun" coins a size of 28-30mm?
The reason why I ask this question is that some coins seem to be "1 mun" coins, even though their size is larger.

2. Related question : do all "2 mun" coins have the number 2 (in chinese character, i.e. two horizontal bars) below the central hole? Some of my coins have the size of a "2 mun" coin, but no number 2.

3. Are there any rare (i.e. valuable) coins among the 88 coins of the collection?

If anyone could  give me the KM# of some of these coins, this would sort of garantee the identification, and I would transfer them to the catalogue (I am by no means an expert).

the personal webpage is at

http://mywoodprints.free.fr/coree/

thanks

Do you have Numista links for these coins? Below are the links to some of your coins in order front top right to left on your website.

https://en.numista.com/catalogue/pieces20506.html
https://en.numista.com/catalogue/pieces41946.html

thank you for this remark, I guess the way to go about it is to look for my coins in the catalogue, that will give me the km#, and possibly a value if it is on ebay.

1. Not size but weight, usually you will need to find the facial value on 17-18th century cash. You should be wary about facial value whenever you have a larger cash coins
2. No, most Korean coins have series numbers that are irrelevant to the value. Look for 當 on later coinage (19th century)
3. Yes all Korean cash are rare, they are the least common and most diverse among the cash-issuing countries (China, Japan, Vietnam, Korea)

David Hartill released a catalogue that lists all Korean cash and all varieties, and I have been looking to buy it and list all coins on Numista, yet I lack the money to buy it ($40+shipping). I was looking to ask Numista for help getting the book, since it is for the greater good of the website, but I do not want to ask for much.

Thank you for this very useful answer.

1. If weight rather than size counts, then does that mean that the size-facialvalue relation given by primaltrek.com is incorrect, or suffers exceptions? Perhaps for older coins?
Why should I be weary of large coins ? Do you mean 40mm? do you mean that larger coins have more chances of being fake?

2. the only coins with that character in my collection are the 5 mun coins, so I have to rely on weight for the others.

The primaltrek site is pretty good for identifying coins. What it lacks is dates of issue.

Citação: manuDThank you for this very useful answer.

1. If weight rather than size counts, then does that mean that the size-facialvalue relation given by primaltrek.com is incorrect, or suffers exceptions? Perhaps for older coins?
Why should I be weary of large coins ? Do you mean 40mm? do you mean that larger coins have more chances of being fake?

2. the only coins with that character in my collection are the 5 mun coins, so I have to rely on weight for the others.

Primaltrek is good for understanding the basics, one of the few websites that even discusses Korean cash coinage. Hartill will be the only source, however, with accurate dates and all varieties.

1. Usually weight goes along with size, so you should expect to see larger coins being of higher facial value. Larger coins do not have chances of being fake, what I am saying is that larger coins tend to have a higher facial value. Newer 19th century cash are much smaller than the earlier cash.

2. You will see higher values more often in later issues, so yes you will have to rely on weight and/or size

thanks again.