Brazil
João Prince Regent gold 4000 Reis 1812-(R) AU58 NGC, Rio de Janeiro mint, KM235.2, LMB-O572B. PROT instead of PORT error - very rare thus. We can only find one other example offered at auction in the last 20 years, which sold in 2002 for $463 hammer.
From the Santa Cruz Collection
HID02901242017
Estimate: 400-600 USD