In London in the mid-1870s, 25 shillings―about $85 in today's terms―went a long way. You could buy 7 grams of gold, 40 liters of rum, or about a half kilogram of opium. Where you couldn't get a bar-gain, however, was the jewelry store. That same amount of money bought just 1 carat, or 0.2 gram, of a gem called tiger's-eye. When rich sources of that precious stone were found in western South Africa in the 1880s, prices plummeted. By 1900, tiger's-eye was considered merely semiprecious. Today, a savvy shopper can purchase the gem for about $1.50 per carat. The passage of time has transformed more than the gem's price. Recent research has upended a 130-year-old theory about how tiger's-eye forms. As a result, scientists soon will be scrambling to update everything from mineralogy textbooks to museum displays.
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