Oban (An old large-sized Japanese gold coin) (大判)
Oban, in the general meaning, is a large-sized oval gold coin among noshikin (flattened by a hammer or roller, that was made of unprocessed gold) made after the 16th century in Japan. It is said that the beginning of standardized oban gold coins were those produced by the Goto family (metal work in Kyoto) under the order of Hideyoshi in 1588. After that, the Goto family (mainly of Kyoto) had produced oban under instructions of the person in power at the time up to 1862. Although ryome (a weighed value) was consistently 10 Ryo (44 monme, approximately 165g) except for those made after 1860, a carat (content of gold) fluctuated over time. The value of oban was not an official price like Koban (former smaller Japanese oval gold coin), and its exchange rate was decided by referring to the market price of the gold contained in the oban.
(For a short period during the Edo period, an official price existed.)
Yuzuriha-kin (mumei-obankin - an unsigned large sheet of gold): a oban in the latter half of the 16th century produced before it was standardized.
Tensho-Oban, those produced from 1588 to 1612. Tensho-hishi-Oban: A lozenge-shaped seal of a paulownia was carved on the surface and the weight was adjusted with submerged gold.
Tensho-naga-Oban: A longer than normal Tensho-Oban. It had been the largest gold coin in the world until the Vienna Philharmonic Gold Bullion Coin weighing 1,000 ounces was minted in 2004.
Daibutsu-Oban (huge Buddha statue Oban): it is said that Hideyori TOYOTOMI had them minted in order to reconstruct Daibutsu-den (the Great Buddha hall) of Hoko-ji Temple in Kyoto. It also has the characteristics of Keicho-Oban-kin.
Keicho-Oban: minted during the Keicho era (around 1601) to the Enpo era (around 1673.)
Keicho-sasagaki-Oban: 'kao' (written seal mark) in India ink looks like the shape of bamboo leaf. This is considered to be the earliest form of Keicho-Oban-kin.
Meireki-Oban: it is said to be coined in Edo after the Great Fire in Meireki. The carat is lower than other Keicho-Oban.
Genroku-Oban: (coined from 1695 to 1716) There is an engraved mark of "元" (Gen) (a carved seal of the name of the period) on the backside.
Kyoho-Oban: (coined from 1725 to 1837) Official price was stipulated as 1coin being equal to 7 Ryo 2Bu.
Tenpo-Oban: (coined from 1838 to 1860) Quite similar to Kyoho-Oban-kin, however, the carat is slightly lower.
Manen Oban: (coined from 1860 to 1862) The ryome is approximately 112g.
There were 2 types characterized by the difference of their surfaces: one is "tagane-uchi (nicking with a cold chisel)" and another is "noshimeuchi (nicking during flattening process.)"
Official price stipulated was that one coin equaled to 25 Ryo.
After the Keicho era oban had four seal marks called 'Gosan no kiri' at four corners in a round frame, and the letters "拾両後藤 (Ju-ryo Goto)" and 'Kao' of the head of the Goto family are written in India ink on the surface. On the backside from the top to bottom, the seal for the name of the period (only for Genroku-Oban-kin), is carved 'Gosan-hadaka-kirimon-kokuin' (literally, 5 and 3 simple engraved paulownia patterns), 'Gosan no kiri' an engraved mark in a circle and a tortoise shell frame, Goto family's Kao mark engraved in a round frame and 3 'zanin-kokuin (engraved marks for the hereditary officers of Kinza and Ginza during the Edo era)' on the left side.
The face value of 10 Ryo was not the real value as currency, but the weight unit of the coin, and in case the weight was in fact less than 10 Ryo, like Manen-Oban, it is expressed as 10 Ryo.