Tokugawa monetary system

Koban Gold Coinage

Koban were oval one-ryō gold coins whose mass, fineness, and diagnostic marks changed across named Tokugawa recoinages.

小判Koban

Context

Historical and monetary setting

The family runs from Keicho through Manen and belongs to declared-value gold, even though its metallic standard was repeatedly adjusted.

Identification

Match the named recoinage through punches, calligraphy, dimensions, mass, fineness context, and specialist references; shape alone is insufficient.

Evidence boundary

The approved Keicho image is a representative pair, not a universal Koban specification or a grading photograph.

Recoinages

Museum catalog comparison values are not authentication cutoffs or measurements of every surviving specimen.

Image	Standard	Start	Catalog mass	Catalog fineness
Representative contextual image: Obverse and reverse of a representative Keichō Koban.↗	慶長小判Keicho Koban	1601	18 g	84%
Not available	元禄小判Genroku Koban	1695	18 g	57%
Not available	宝永小判Hoei Koban	1710	9 g	84%
Not available	正徳小判Shotoku Koban	1714	18 g	84%
Not available	享保小判Kyoho Koban	1715	18 g	87%
Not available	元文小判Genbun Koban	1736	13 g	66%
Not available	文政小判Bunsei Koban	1819	13 g	56%
Not available	天保小判Tempo Koban	1837	11 g	57%
Not available	安政小判Ansei Koban	1859	9 g	57%
Representative contextual image: Obverse and reverse of a representative Man’en Koban, retaining its oval form.↗	万延小判Manen Koban	1860	3 g	57%

Image	Standard	Start	Catalog mass	Catalog fineness
Not available	慶長丁銀・豆板銀Keicho Chogin and Mameitagin	1601	—	80%
Representative contextual image: One face of a representative Genroku Chogin.↗	元禄丁銀・豆板銀Genroku Chogin and Mameitagin	1695	—	64%
Not available	宝永二ツ宝銀Hoei Futatsuho Silver	1706	—	50%
Not available	宝永三ツ宝銀Hoei Mitsuho Silver	1710	—	32%
Not available	宝永永字銀Hoei Eiji Silver	1710	—	40%
Not available	宝永四ツ宝銀Hoei Yotsuho Silver	1711	—	20%
Not available	正徳銀Shotoku Silver	1714	—	80%
Not available	元文銀Genbun Silver	1736	—	46%
Not available	文政銀Bunsei Silver	1820	—	36%
Not available	天保銀Tempo Silver	1837	—	26%
Not available	安政銀Ansei Silver	1859	—	13%

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Evidence

These links support the claims on this page. Source authority does not imply permission to republish source images.

Early Edo Gold Recoinages Bank of Japan Currency Museum

Keicho through Kyoho Koban display-table masses and fineness values.

Open source

Later Edo Gold Recoinages Bank of Japan Currency Museum

Genbun through Manen Koban and Tempo Goryoban display-table masses and fineness values.

Open source

Non-destructive Analysis of the Fineness of Kobans in the Yedo Period Institute for Monetary and Economic Studies, Bank of Japan

Analytical measurements, specimen variation, and qualification of nominal fineness.

Open source