Momme (unit)

Momme (匁) is both a Japanese unit of mass and former unit of currency. As a measurement, Momme is part of a table of Japanese units where during the Edo period it was equal to $1/10000$ ryō (aka Tael). Since the Meiji era 1 momme has been reformed to equal exactly 3.75 grams. The latter term for Momme refers to when it was used as a unit of currency during the Edo period in the form of silver coins. As a term, the word "Momme" and its symbol "匁" are unique to Japan. The Chinese equivalent to Momme is qián, which is also a generic word for "money". While the term Momme is no longer used for currency, it survives as a standard unit of measure used by pearl dealers to communicate with pearl producers and wholesalers.

Origin
The Japanese word Momme first appeared in a family book by the Ōuchi clan during the Bunmei era in 1484. In the English language the word first appears in the early 1700s per the Oxford English Dictionary, which first traces its usage to Johann Jakob Scheuchzer in 1727.