Wondering if a crystal is real? Learn the differences between natural, synthetic, treated, and imitation crystals, plus practical clues that can help you recognize dyes, treatments, common fakes, and other warning signs before you buy.

What do Herkimer Diamonds, Lake Superior Agates, Oregon Sunstone, and Bisbee Turquoise have in common? They're among the most iconic rocks, minerals, gemstones, and fossils found in the United States. In celebration of America's 250th birthday, we're taking a coast-to-coast look at ten legendary specimens that have inspired collectors, rockhounds, and gemstone enthusiasts for generations.