Gem Valley is a rural valley in Caribou County, Bannock, and Franklin counties in Idaho, United States, so named for its local gemstones which can be found throughout the valley. It is approximately 20 miles (32 km) wide at its widest point east to west, and 60–70 miles (97–113 km) long north to south. By local definition, Gem Valley originates at the to the north, and terminates at the to the south.