--- title: "To-hyaku Coins (Large-type Tenpo Tsuho)" url: "https://ittendo.com/en/coinpedia/ana-sen-009-tohyakusen" site: "ITTENDO" type: "coinpedia" category: "ana-sen" series: "Holed Coins" lang: "en" --- # To-hyaku Coins (Large-type Tenpo Tsuho) > Conclusion: Tenpo Tsuho symbolizes late Edo-period economy; the diversity of Honza and Mitsu-chu-sen creates collecting and investment value. - 時代: 江戸 - 素材: 銅 - 額面: 文 - 発行量: 大量 - 価格帯: 中堅 ## Overview of the Tenpō Tsūhō: The Large Coin That Supported the Late Edo Economy The Tenpō Tsūhō (天保通宝) is a large denomination coin with a face value of 100 mon, first minted in the late Edo period in Tenpō 6 (1835). Its distinctive feature is its beautiful elliptical shape, modeled after the koban coin. Measuring approximately 49mm in length and 33mm in width, it stood out among the hole coins of the time. The coin is characterized by a rectangular hole in the center, the inscription "天保通寳" on the front, and "當百" on the back. The weight is around 20.6g, making it considerably heavier than previous hole coins. However, despite its 100 mon denomination, the actual copper content was far less, reflecting its role as nominal currency created to address the shogunate's financial difficulties. During this period, Japan was troubled by repeated famines and worsening finances. The shogunate sought to stabilize its finances by repeatedly re-minting coins and adjusting the money supply. The Tenpō Tsūhō emerged from such economic circumstances and became a symbol of the late Edo period. Due to its unique shape, it was commonly known as "Tenpō Sen" and became deeply integrated into people's lives. ## Minting and Circulation History: Influence Beyond Its Denomination Minting of the Tenpō Tsūhō began under the supervision of the Gotō family of the Kinza in Edo. However, due to subsequent financial difficulties, clandestine minting (mittsu) started in various domains across Japan. Powerful domains such as Satsuma, Tosa, Mito, and Aizu began producing clandestine coins to rehabilitate their finances. The proliferation of clandestine minting starkly illustrates the shogunate's declining control and the domains' aspirations for economic independence. The Tenpō Tsūhō continued to support Japan's economy for about 36 years until its circulation was halted in Meiji 4 (1871) following the Meiji Restoration. During this period, despite its 100 mon denomination, its actual value was approximately 80 mon. Even though its face value was lower from the start, the coin's high denomination made it widely accepted, especially fulfilling the role of compensating for the shortage of small denomination coins in rural areas. With the transition to a new currency system, its role ended, but its influence remains immeasurable. The history of the Tenpō Tsūhō can be said to reflect the economic history of the tumultuous late Edo period. For more details on [identifying and valuing the Tenpō Tsūhō](/coinpedia/ana-sen-003-tenpo-tsuho), please refer to the detailed article. ## Classification of Authorized Coins and Clandestine Coins: Basics of Identification The Tenpō Tsūhō is broadly classified into "honza coins" (本座銭) and "clandestine coins" (密鋳銭) based on their place of production. Honza coins were minted at government-authorized mints like the Kinza or Ginza and are generally characterized by sharp inscriptions and high-quality copper. They closely adhere to the specified weight and are known for their overall high quality, circulating as the official currency reflecting the shogunate's prestige. In contrast, clandestine coins were produced without authorization by various domains under financial distress to boost their own economies. As a result, these often exhibit deteriorations in character form and copper quality with inconsistent quality compared to honza coins. However, some clandestine coins, like those from Satsuma Domain, are of such high quality they are sometimes indistinguishable from honza coins, posing a challenge even to experts. Identifying the origin of clandestine coins is a major theme in collecting Tenpō Tsūhō and is the source of much depth. Beginners entering this world should first understand the fundamental differences between honza coins and clandestine coins. To learn more about [identifying fakes and forgeries](/coinpedia/basics-004-fakes), it's important to first grasp the characteristics of genuine coins. ## Characteristics and Rarity of Clandestine Coins by Origin: A Collector's Quest The true charm of collecting clandestine Tenpō Tsūhō lies in identifying their origin. Coins with confirmed origins hold high collector value due to their historical background and rarity. Each domain's minting techniques and financial conditions are reflected in the quality and inscriptions of the coins, necessitating detailed observation. For example, coins from the Satsuma domain have very good copper quality and tend to be slightly heavier (approximately 21–22g). Mito domain coins feature distinctive long vertical strokes in the "天" character, and Tosa domain coins are noted for their narrower rims. Additionally, Aizu and Sendai domain coins showcase their own unique inscriptions and minting traces. Determining origin requires a comprehensive evaluation of factors like inscriptions, weight, copper color, rim shape, and minute minting marks. The process of analyzing these in comparison with specialized books and past identification cases is the greatest enjoyment in this field. Origin-verified coins can be appraised anywhere from 50,000 to 150,000 yen or more, reflecting their rarity. The determination of [factors that impact the value of ancient coins](/coinpedia/basics-001-value-drivers) is varied, with the identification of clandestine coin origins being a prime example. ## Key Points in Appraising Honza Coins: Authenticity Lies in the Details When appraising honza coins, the brushstrokes of the characters and the overall balance serve as key evaluation criteria. First and foremost, check ① the uniformity of the horizontal strokes in the "天" character. In honza coins, these strokes are typically evenly spaced. Next, focus on ② the flow of the stroke in the right side of the "保" character's radical (ninben). A smooth and strong brushstroke is one of the characteristics of honza coins. Additionally, ③ the balance of the "當百" characters on the reverse and the arrangement of the "百" character are crucial points. Ensure that the characters are stably placed, particularly paying attention to whether the strokes of the "百" character are neatly rendered. ④ The thickness and uniformity of the rim also indicate the quality of honza coins. Standard honza coins typically weigh 20–21g, with a long diameter of 49–50mm and a short diameter of 32–33mm. Coins that deviate significantly from these standards or exhibit prominent distortion in characters are likely to be clandestine or counterfeit. As basic tools for appraising old coins, a scale capable of measurements in 0.1g increments and a ruler for precise measurement are essential. Mastering the use of these tools and observing details closely is the first step in honing your appraisal skills. By understanding the [standards of coin grading](/coinpedia/basics-003-grading), more objective evaluations can be conducted. ## Beware of Modern Counterfeits: Identifying Cleverly Made Fakes Due to its distinctive shape and historical value, Tenpō Tsūhō has many modern forgeries circulating in the market. These counterfeits are often made for souvenirs, toys, or educational materials, but some are maliciously sold as authentic items. Beginners must be extremely careful not to make purchases based solely on appearance. To distinguish forgeries, the primary factor is weight. Modern counterfeits tend to be markedly lighter, around 12–15g, compared to authentic coins (approximately 20.6g). Next, examine the surface finish. Forgeries lack the casting texture typical of authentic coins, appearing smooth due to being uniformly pressed by molds. Additionally, lack of natural patina from years of circulation or the presence of unnatural finishes requires attention. Purchasing from antique markets or stalls involves high risk, thus requiring careful judgment. It's wise to purchase from trusted numismatic dealers by verifying the texture and weight of authentic pieces and choosing coins with a certificate of authenticity. Knowledge to discern forgeries is crucial, and consulting [fake detection guides](/guide/fake-detection) can help develop such skills. ## Distinguishing Early, Middle, and Late Stages by Size and Weight: Unraveling History Honza coins of the Tenpō Tsūhō exhibit slight differences in specifications depending on the minting period, affected by the evolution of minting technology, material procurement circumstances, and changes in mass production systems. Coins minted in the early period (around Tenpō 6–10) tend to be slightly heavier with thicker rims. Coins from this period were relatively meticulously made, with many exhibiting high copper quality. As mass production systems were established in the mid-period, standards stabilized, and weights showed a slight reduction trend. Approaching the late Edo period, as fiscal woes and material shortages arose, there was a noticeable decline in copper quality and casting craftsmanship. The method of determining minting period by weight and thickness measurement is established among Tenpō Tsūhō researchers. Early coins often receive slightly higher evaluations than mid- or late-period coins due to their rarity and superior quality. Additionally, trial coins or special mother coins with different specifications from regular issues exist, forming an integral part of [varieties and classification systems of ancient coins](/guide/varieties). Gaining knowledge about distinguishing these enhances the depth of collection. ## How to Enjoy and Begin Collecting: Entering the World of Tenpō Tsūhō Collecting Tenpō Tsūhō captivates many enthusiasts because of its unique allure. For beginners, it is highly recommended to first purchase a high-quality honza coin from a trusted numismatic dealer. Starting with one excellent coin, priced around 5,000 to 10,000 yen, allows you to physically experience the genuine texture and weight, forming the first step in collecting. Next, prepare a scale with 0.1g precision and a ruler, and develop the habit of measuring your newly acquired Tenpō Tsūhō. This practice enables you to detect specification differences and signs of clandestine coins on your own. Additionally, obtaining specialized books featuring clandestine coin classification charts and attempting script comparisons will draw you into the deep world of Tenpō Tsūhō. Don't forget to implement [proper storage methods for old coins](/coinpedia/basics-006-hokan) to protect your valuable collection. The elliptical and large Tenpō Tsūhō boasts exceptional visual presence among ancient coins. It offers the satisfaction of decorating your collection as a "face" and allows you to enjoy the pleasure of holding history in your hands. Refer to the [guide on sources and methods of purchasing ancient coins](/coinpedia/basics-008-shotai) to find your own Tenpō Tsūhō.