7- 1868 United States Benjamin Franklin Z-Grill 1c blue – $930,000
Known among collectors as one of the rarest stamps from the US, the 1c Benjamin Franklin Z-Grill was imprinted in only few exemplars with Z-shaped “grill” that gives it its name.
Most US stamps of the era are pressed with a grill to leave a pattern of indentations, allowing cancellation ink to take and to avoid forgeries.
But not the experimental Z-shaped grill which features horizontal indentations that were found to be unsuitable for the issue.
The grill was quickly replaced, leaving behind just two known examples. One of these sold at auction for $930,000, in 1998.
