(1837-1843) 5 Ryo Gold UNC

●This is an uncirculated example of the Tenpō Goryōban (天保五両判金), a rare gold coin minted in the late Edo period. With deeply struck, sharp hallmarks, this coin displays exceptional detail and brilliance.

The Goryōban sits between the koban (小判) and ōban (大判) in both size and denomination. While it adopts the same hallmarking system (極印) as the koban, the circular marks on each side are exclusive to the ōban, giving this coin a hybrid design—a fusion of both large and small denomination aesthetics.

However, the Goryōban was ultimately rejected by the market. The problem lay in the mismatch between its declared value (5 ryō) and its actual gold content.

• Tenpō koban: 11.2g, 56.8% gold → 6.36g pure gold

• Tenpō Goryōban: 33.75g, 84.2% gold → 28.42g pure gold

A coin worth 5 koban should have had:
6.36g × 5 = 31.81g of pure gold

But the Goryōban contained only 28.42g, resulting in a shortfall of about 3.39g—equivalent to more than half a koban’s worth of gold. This discrepancy eroded public confidence and led to its failure in circulation.