<p>Jewel, 42, is one of four artists on this list who goes by just one name. (The others are Madonna, Adele, and Enya). Jewel made this list mostly because of the success of her 1995 debut, Pieces of You. That album is certified for U.S. shipments of 12 million. (Photo: Evan Agostini/Invision/AP) </p>
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