How to Identify the Japanese Bu / Ichibu-gin (silver bar coin)

What It Is

Ichibu Gin was a rectangular silver plate currency used in Japan during the Edo period, valued at one bu (one-quarter ryo) within the Tokugawa shogunate's gold-based monetary system. Several successive issues (including the Tenpo, Ansei, and Meiji-era types) were struck between the 1830s and 1860s as the government periodically adjusted silver content. Because it was pegged directly to the gold-based bu/ryo system rather than valued purely by its own silver weight, it functioned more like a fixed-value token coinage than typical Western silver coins, which is why the government's official stamps guaranteeing its value were so central to the design.

Obverse Design & Inscriptions

The plate is stamped with the paulownia (kiri) crest used by the Edo mint authority (Ginza), along with the character "定" (meaning "fixed" or "set value") and the denomination "一分" (ichi bu), all within a raised border.

Reverse Design & Inscriptions

The reverse is often plain or carries additional small stamps added by silver assayers or mint inspectors (sometimes called kiritsuke), confirming the piece had been checked and approved.

Size, Weight, Metal & Edge

Unlike round coins, Ichibu Gin is rectangular, roughly 25 x 15mm. It is a silver alloy, with weight and fineness varying by issue — generally in the range of 8.6 to 11 grams — with later issues typically more debased than earlier ones. Edges are plain-cut rather than milled.

Mint Marks & Where to Find Them

Identification relies on the stamped crest and characters applied by the Edo Ginza (silver mint) rather than a modern numeral mint mark. Comparing the exact style of the crest and additional inspector stamps helps narrow down the specific issue period. Reference catalogs of Edo-period silver currency list the subtle character-font and border differences that distinguish, for example, a Tenpo-era Ichibu Gin from a later Ansei or Meiji-era piece.

Telling It Apart from Similar Coins

Distinguish Ichibu Gin from other Edo-period silver denominations, such as Isshu Gin (valued at one-sixteenth ryo), primarily by size and by the denomination character stamped on the face — "一分" identifies this specific bu value.

Judging Condition at a Glance

Look at how crisply the stamped crest and characters were struck, and check that the raised border rim is intact and not excessively worn or bent. Because these plates were carried loose in purses and often clipped together with other denominations, minor edge nicks and light surface scratches are common even on otherwise well-preserved examples.

Authenticity Red Flags

Collector reproductions of Ichibu Gin exist, particularly for souvenir markets. Genuine pieces show crisp, punch-stamped (not cast) lettering, correct weight for the specific issue, and wear patterns consistent with handling on the high points of the stamps. Cast copies often display soft, blurred lettering and an incorrect thickness or weight.