These are the most valuable stamps from around the world ... The Benjamin Franklin Z Grill is a 1-cent stamp from 1868 created with a briefly used grill that left tiny Z-shaped indentations.

A 1-cent postage stamp from 1868 is up for auction and could fetch up to $5 million. A New York auction house is selling what it calls “America’s Most Valuable Postage Stamp”—a 1-cent “Z ...