20 000 Reis Bolama seal

The Banco Nacional Ultramarino was the sole institution authorized to issue banknotes across Portuguese overseas territories, and this 20,000 Réis belongs to the series overprinted for Guinea — specifically validated for circulation through the Bolama branch, then the colonial capital. The "Bolama seal" designation distinguishes it from otherwise identical plates prepared for other BNU territories; the same Bradbury Wilkinson printing served multiple colonies, differentiated only by the validation stamp applied before release.

Bolama lost its status as capital to Bissau in 1941, which puts a hard ceiling on how long notes bearing this seal could have remained in active use.