In 1221, in what we now call Turkmenistan, a captive held by Mongol soldiers confessed that she had swallowed her pearls in order to safeguard them. She was immediately executed and eviscerated. On finding several pearls, Chinggis Qan (Genghis Khan) ordered that they cut open every slain person on the battlefield. Pearls, valued for aesthetic, economic, religious, and political reasons, were the ultimate luxury good of the Middle Ages, and the...