A new analysis of U.S. mineral data reveals that California, Arizona, and Nevada lead the nation in gemstone resources, while Wyoming has quietly overtaken Arkansas as the state with the most known diamond sites.
The study, conducted by manufacturing software engineers at MRPeasy, analyzed data from the U.S. Department of the Interior’s Mineral Resources Data System. Researchers identified 1,211 documented sites across the United States that contain precious and semiprecious gemstones.
To focus on potentially active deposits, the study excluded sites labeled as “past producers,” meaning locations where resources had already been exhausted. Although the database was last updated in 2011, it remains one of the most comprehensive mineral records in the country.
California ranked first with 297 known gemstone sites, far ahead of other states. Most of these locations are broadly categorized as gemstone deposits containing minerals such as beryl, jasper, kunzite, topaz, chalcedony, tourmaline, and others. The state also has 13 garnet sites and two diamond sites.
Arizona placed second with 170 active gem sites, including 92 gemstone locations and 64 semiprecious gemstone deposits. Arizona also contains 13 garnet sites and a diamond site in Yavapai County. According to the U.S. Geological Survey, Arizona recorded the highest value of natural gemstone production in 2024.
Nevada ranked third with 167 gemstone locations, including 129 gemstone sites and 31 semiprecious gemstone deposits. The state also hosts several garnet and sapphire deposits.
While California leads overall, Idaho dominates the United States’ garnet resources. Of the country’s 255 known garnet sites, 77 are located in Idaho, making it the nation’s primary center for the mineral. Garnet is widely used as an abrasive material in industrial processes such as waterjet cutting and abrasive blasting.
The analysis also reshapes the traditional perception of the “Diamond State.” Arkansas has long been associated with diamond mining, but the study found Wyoming now leads the country in active diamond sites, with 10 known locations. Montana follows with nine, while Arkansas and Alaska each have eight.
Researchers emphasize that the number of sites does not necessarily reflect the quality or economic significance of the deposits.
Alaska stands out for another reason. It is the only U.S. state known to contain jade deposits, with six documented sites. Rubies are even rarer, appearing in only two known locations in the entire country, one in North Carolina and one in Wyoming.
North Carolina also holds historical significance for emerald mining. Although emeralds were once recorded at four sites in the state, those locations are now classified as past producers, suggesting commercial extraction has ended.
Industry experts note that market trends have also influenced gemstone demand in recent years. Karl Heinrich Lauri, chief marketing officer at MRPeasy, said the global luxury market slowed in 2024 while synthetic diamonds gained popularity.
“Global demand for luxury goods declined in 2024 while lab-grown diamonds became more common,” Lauri said. Sanctions on Russian-produced diamonds also pushed many U.S. buyers toward alternatives.
Beyond jewelry, gemstones such as garnet play a major role in manufacturing. Garnet abrasives are widely used in aircraft and automotive production, particularly in waterjet cutting and industrial blasting. According to industry data, processed garnet generated about $50 million in revenue for U.S. companies last year.
Despite the MRDS database’s age, geological experts say it still offers valuable insights into the distribution of mineral resources across the country.
The findings highlight the remarkable diversity of American gemstone deposits, from jade in Alaska and sapphires in Montana to rubies in North Carolina and diamonds in Wyoming, showing that the United States holds a surprisingly broad range of natural gemstone resources.
