Diamonds aren't the only gems that have the power to rescue people from financial ruin. Mexican black pearls have saved many from misfortune.

    When the Bolsheviks seized the reins of Russian government in October 1917, they began executing nobles as fast as they could arrest them, Prince Felix Youssoupov, Czarist Russia's Donald Trump, fled for Paris with every jewel he could sew in the linings of his luggage. The greatest of his treasures was a Mexican black pearl necklace owned by Catherine the Great (1729-1796) and given by her to his mother.

    In 1922, Felix fell on hard times and asked jeweler Pierre Cartier to sell the strand. It fetched $400,000 from an American heiress-as much money as any Rembrandt painting then fetched at auction.

    New World black pearls, principally from the Gulf of California (also known as the Sea of Cortez)-were cornerstones of Old World wealth from 1500 until 1850. Besides Catherine, their admirers included Marie Antoinette and Princess Eugenie, consorts and then wives, respectively, of Napoleon Bonaparte and Napoleon III.

    Cortez Pearls, cultured in limited-edition harvests in Mexico, are identical in beauty to those that captivated the courts of Europe when Spanish explorers started sending them home in the early 1500s.