From Marteau

Japanese unit of weight (3.75 g) used to measure quantities of coined silver in a decimal system of 1 kamme = 1000 momme, 1 momme = 100 Fun = 100 Rin. A debasment of Japan's coinage could hence only be performed by changes of the fineness of metal minted. Silver had been coined with a fineness of 80 percent in the 17th century, the fineness was reduced after 1695 in several steps from 50 to finally 20 percent before better silver was brought back onto the market in 1714.

See Money (Japan)

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