China - Japanese Occupation Fiber Coins (1944-1945)

At the end of WWII Japan was issuing "occupation of China" coins struck on "fiber".
They were 1 Fen coins (1945) and 5 Fen coins (1944 & 1945).
Krause lists two color varieties, red and brown.

I haven't been able to find information, particularly with images, that define the two colors.
Can anyone point me to a resource that will clarify the color differences?

 

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Google image search came up with this. Some of the images are associated with websites. Porcelain color may be the factor,but not certain. I hope this is helpful.

https://www.google.com/search?q=1 Fen coins (1945) and 5 Fen coins (1944 & 1945)&biw=1280&bih=923&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwi_95qY98HRAhWq6oMKHfmNBRgQsAQINA

 

Very nice.

I like studying the history of a country through its coins.

 

Thanks for the site.
More than i could find.
Now I need to work it through.

 

The JNDA book, issued annually by the Japanese Numismatic Dealers Association, has a section on "Occupied Territories Coins," but is only available in Japanese. Under "Manchurian Coins" I see a number of 5 and 1 Fen coins, but only references to "Red Fiber." The rest are cupronickel, aluminum or copper. I don't see any references to "brown fiber" Fen coins.