There is one state in the U.S. known for producing gem-quality sapphires; that place is Montana.
The history of sapphires in Montana begins with gold miners in the 1860s who noticed the sapphires while mining for gold. Thus, Montana sapphires were officially discovered in 1865 but were not mentioned in writing until 1873 when the American Journal of Science reported its discovery.
Montana sapphires have been mined in the state for more than 100 years. They are the only state in the U.S. with significant production of sapphires.
Unlike other sapphires, Montana sapphires were initially not considered to be a popular commodity. The reason for this is due to their coloration. Instead of the expected blue colors for a sapphire, most Montana sapphires are lighter in color and range from pale green to blue-green. They also exist in fancy colors such as yellow, orange, violet, and pink. However, there is a growing appreciation for these sapphires.
There were four mining areas in Southwestern Montana for the sapphires. They were located in the Upper Missouri River, Dry Cottonwood Creek, Rock Creek, and Yogo Gulch.
The sapphires from the Yogo Gulch area were particularly found to be valuable after they were analyzed by jewelry experts from Tiffany & Co.
Today, some of the most abundant sapphire deposits can be found by the Missouri River near Helena Rock Creek in the Sapphire Mountains and Dry Cottonwood Creek near Deer Lodge.