Complex sentence: The Jewelry District is a section of Downtown Los Angeles where a variety of jeweled products are sold and, according to the Los Angeles Convention Center and Visitor's Bureau, it is the largest jewelry district in the United States.
Split into simpler sentences: The Jewelry District is a section of Downtown Los Angeles where a variety of jeweled products are sold. According to the Los Angeles Convention Center and Visitor's Bureau, it is the largest jewelry district in the United States.