[JK-073] Kyoho-Sado Koban Gold

Until around 1897 (Meiji 30), coins of this type were generally classified as Sado Koban. As scholarly research progressed and die studies became more precise, this category was redefined, and such pieces are now properly classified as Kyōhō Sado Koban, a distinct subtype within Tokugawa gold coinage.

True original Sado Koban can be identified by the presence of the character “神” (Kami) within both the tōryō-in (chief assayer’s mark) and the zajin-in (mint official’s mark) located on the lower left area of the reverse.
This diagnostic feature is absent on the present coin, confirming that it was originally a Kyōhō Koban rather than a separately struck Sado issue.

Accordingly, the metal composition and fineness are identical to standard Kyōhō Koban, as expected. The later addition of the “Sa” (佐) countermark signifies an association with Sado Island, home to Japan’s most important gold mine during the Edo period, but does not indicate a separate original strike.

What distinguishes this particular example is the exceptionally well-preserved stone-grain texture (ishime) on the reverse.
While many Kyōhō-period koban with Sado countermarks exhibit weak or uneven surface texture, this piece displays a remarkably clear, natural, and evenly flowing ishime, produced during the original striking process. The clarity of this texture significantly enhances both the aesthetic appeal and the collectability of the coin, making it a standout example within the Kyōhō Sado Koban category.

Specifications
Kyōhō Sado Koban
Purity 86.1% / 17.7g