Mines.

U.S. production of commercial gems includes agate, beryl, freshwater pearl, garnet, jade, jasper, mother-of-pearl, opal, peridot, quartz, sapphire, tourmaline, and turquoise.

Except for the few gem diamonds found each year in Arkansas, U.S. diamond production is very low.

Yet exploration for diamonds continues in Alaska, Colorado, Michigan, Minnesota, Wisconsin, and Wyoming. A diamond mining project at the Crater of Diamonds State Park in Arkansas is still being evaluated by the State.

World diamond reserves are estimated to be about 300 million carats, including near-gem materials but not diamonds of abrasive quality.

Most of the reserves are in southern Africa, Siberia, and western Australia. It is difficult to estimate reserves because the value of a given deposit varies with the market for the gems.

Jade nephrite, China.

The Hope Diamond, India.

Chemical formulas of gemstones