Kyōhō Koban's Genesis Background
Kyōhō Koban (享保小判) began minting in 1715 (Shōtoku 5, illustrated catalogue). According to the Currency Museum's 'History of Japanese Currency,' the shogunate, on the advice of Arai Hakuseki, re-minted currency in 1714 to raise it to the same quality as Keichō gold and silver (Shōtoku reminting), and the following year in 1715, further improved the quality of the Koban (Kyōhō Koban). The permanent exhibition catalogue states that the reminting of Shōtoku and Kyōhō was advanced by Arai Hakuseki, who served under the 6th shogun Ienobu and the 7th shogun Ietsugu. Tokugawa Yoshimune became the 8th shogun in the Kyōhō era (1716) (according to the National Archives' chronology), after the start of Kyōhō Koban minting (1715). It achieved an 86.8% gold quality (regulated quality), surpassing about 84% of the Keichō Koban, and a weight of about 18g (illustrated catalogue). Definitive records of its minting amount are not confirmed (research estimates will be added as sources become available).
Shōtoku and Kyōhō Reminting and the Genbun Reminting
The Currency Museum's 'History of Japanese Currency' notes that the Edo shogunate responded to the price increase from Genroku reminting by adopting Arai Hakuseki's suggestion in 1714 to raise the quality to that of Keichō gold and silver (Shōtoku reminting), leading to a sharp decline in the money supply and resulting in economic stagnation and falling prices. In 1715, the quality of the Koban was further enhanced (Kyōhō Koban), making Shōtoku and Kyōhō reminting the only reminting during the Edo period to increase gold and silver quality, as recorded in the Currency Museum's 'History of Japanese Currency'. According to the museum, the shogunate later responded to rice price declines from the Shōtoku and Kyōhō remintings by increasing the circulation of gold and silver currency by lowering their quality in 1736 (Genbun reminting). The evolution of currency policy during the Edo era is also explained in Types and Price Ranges of Koban.
Specifications and Features of Kyōhō Koban
Kyōhō Koban's quality is recorded as 87% (rounded value) in the remodeling table of the permanent exhibition catalogue, the highest among Edo Koban in the table. The regulated quality from Kinza records is 86.8% (50.7 kō value). Its weight is 18g (rounded value) as per the illustrated catalogue, the same as the Keichō Koban. Ueda Michio's paper (Monetary Research, 1993) reports a non-destructive analysis of three specimens owned by the Bank of Japan's Monetary and Economic Research Institute, showing a gold content of 85.7-86.6% and a weight of 17.70-17.75g. Dimensions, gold content, and existing conditions were not verified in the references consulted. Individual prices and auction examples are only included in market records if verified records with date, lot, source URL, and confirmation date are obtained.
Inscriptions and Design of the Obverse and Reverse
The obverse of the Kyōhō Koban features the characters "壹両" and a kaō (a seal or stamp). The manufacturing of gold coins was directed by the Gotō family, and the manufacturing site within the Gotō office grounds in Nihonbashi became known as Kinza, as noted in the permanent exhibition catalogue. For distinguishing it from the Shōtoku Koban, Ueda Michio's paper (Monetary Research, 1993) refers to the "Hanare Mitsutsugu" (the "光" and "次" characters being separated imprinted), positioning it as circumstantial evidence proposed post-war. The purpose of the script and pattern on the reverse inscription has not been confirmed in the references consulted.
Comparison with Other Edo Koban
The remodeling table in the permanent exhibition catalogue lists Keichō Koban (1601) 84%・18g, Genroku Koban (1695) 57%・18g, Hōei Koban (1710) 84%・9g, Shōtoku Koban (1714) 84%・18g, Kyōhō Koban (1715) 87%・18g, Genbun Koban (1736) 66%・13g (all rounded values). Kyōhō Koban boasts the highest quality among the Koban in this table. Please also refer to the Keichō Koban section.
Evaluation Points and Authenticity Determination
When examining an individual piece, key indicators include the kaō on the obverse and the "壹両" character stamp, the shape of the inscription, and its weight. According to the illustrated catalogue's table, the weight is 18g (rounded value), serving as a reference point when comparing the individual weight. Distinction from Shōtoku Koban, as per Ueda Michio's paper (Monetary Research, 1993), uses "Hanare Mitsutsugu." The description that high quality leads to less discoloration and rust was not found in the consulted references. Authentication relies on a comprehensive judgment of multiple features and provenance, with no known method concluding from a single characteristic. General precautions for distinguishing counterfeits and altered items are available in the Guide for Detecting Fakes and Altered Items.
Rarity and Current Condition
Definitive records of minting amounts are not confirmed (research estimates will be added upon source verification). However, due to subsequent circulation, usage, and reminting or melting into Genbun Koban, high-condition surviving pieces are limited. Records indicating the number of well-preserved pieces were not found in the consulted references. Even generic average pieces hold historical value by surviving nearly 300 years. As condition greatly influences price, understanding the Grading Standards for Old Coins is important.
Handling Market Records
Auction records confirmed as Kyōhō Koban are not yet in Ittendo's market records. The general market for the entire type is not presented as the price for this currency type. Instructions for reading auction records can be found in Introduction to Ancient Coin Auctions and Their Use. Only records verified with dates, lot numbers, source URL, and confirmation dates will be included in market records for individual prices and auction examples.
Precautions in Purchase and Storage
When purchasing Kyōhō Koban, verify the inscriptions, kaō, and weight against catalogues and records, along with the history. References did not confirm the existence or methods of counterfeits and modifications. Additionally, post-purchase storage is crucial. Humidity, sudden temperature changes, and physical shock can deteriorate Koban. Keep it in specialized coin capsules or albums and store in a dark place. More details on proper storage methods can be found in Proper Storage Methods for Ancient Coins. Maintaining storage and authentication records provides valuable future verification clues.