Here's a beautiful original example of a Korea 2 Mun coin (1742-1752), Seoul Charity Office mint. I've made several trips to Korea with my wife and always looked for coins along the way. 99%+ of what I saw were fakes, but I found a group of about 30 coins in a metal bowl at an antique dealer I visited while she was shopping for art supplies. They were all the real deal and were apparently part of a small hoard that was dug up somewhere. This was probably the nicest one.
Don't know anything about these. What makes this a "gem"? Because it certainly isn't gem grade (MS-65 or higher)
I call it a gem because of the beautiful original patina. The coin was probably struck shortly before it was buried. I basically look for sharp, clear detail on coins like this. Almost anyone can tell a cast copy of a struck coin but the same rules also apply to cast coinage. Forgers of these in Asia use original coins to make molds of fake cash pieces. A cast of a cast coin will have noticeably less detail than the original. A lot of it also comes with experience in knowing what original cash pieces look like.
