Here's an interesting TPG designation: "Altered Color". I have my own suspicions as to why this was done, but thought it might spark a discussion, especially if anyone has seen other examples of "altered color" on other World Coins. The coloring is so obvious on this coin. You can see that the "colorizing juice" ran into the recesses and has pooled in places, like the edges of the coins at the 6 o'clock position on the reverse and obverse.
This coin is a bit interesting. For those who don't know the history of Korean coinage, 1970 is a transitional year for 5 and 10 won coins. Due to the higher copper prices, copper content was dropped from 88% to 65% (could be wrong - writing this from memory) and the rest being zinc. Needless to say, the older coin is worth significantly higher in UNC condition. I would not be too surprised if someone tried to dip it to give a better look.
