What state has the most gemstones? A quarter of the states produce the majority of the gemstones in the country. In decreasing order of production value, Idaho, Arizona, Oregon, California, Montana, Arkansas, Maine, Colorado, North Carolina, Nevada, Texas and Utah produced 90 percent of the U.S.'s natural gemstones last year, the USGS said.Sep 15, 2017 What states can you find gemstones? Oceanview Mine. San Diego County, California. ... Royal Peacock Opal Mine. Denio, Nevada. ... Gem Mountain Sapphire Mine. Philipsburg, Montana. ... Crater of Diamonds State Park. Murfreesboro, Arkansas. ... Emerald Hollow Mine. Hiddenite, North Carolina. Where is the best place to gem hunt? Top Spots for Gem Hunting in the US Crater of Diamonds State Park. ... Gem sluice, Hiddenite, NC. ... Crater of Diamonds State Park. ... Rutile find. ... Gem Mountain, Philipsburg, MT. ... Topaz in situ. ... Three pieces of opal from Virgin Valley, Nevada. What is the gem capital of the world? Franklin, North Ca