I finally completed this difficult set when Korea was occupied under Japan back then. Japan was striking coins for Korea and as the economy in Japan struggles after the Russo-Japan war in 1904-5, the Korean coinage also takes a hit.
The first of the large size Korean won was struck in 13.5g planchets in 1905 and 1906.


In 1907, all silver and copper coinage had their contents reduced. This silver coin was reduced down to 10.0g. The half won was struck for another 2 more years and this is the end for this series.


So how tough are these coins? Quite.
Mintage are as follows:
1905 - 0.6 million
1906 - 1.35 million (Japanese sources quote 1.2 million)
1907 - 1 million
1908 - 1.4 million
For coins that were struck in terms of millions, there should be plentiful of these coins. Not so true. As the Japanese economy dives war after war, it is not known how much coins were recalled from Korea to be melted down. Even after the war, the Koreans were furiously getting rid of anything that had to do with Japanese occupation. It is not known how much of these coins survived, but I am suspecting that only a mere fraction did.
While these coins used to be common for sale, they seem to have vanished from the marketplace otherwise being pricy if you can find one. I find that the mintage doesn't really reflect how difficult it is to locate a couple of the years. I personally rate it as follows - 1906 being the easiest.
1906, 1907, 1908, 1905
Note that I rate 1908 coin harder to find than the 1907 despite the higher mintage.
Hope you enjoyed reading!