When sourcing pearl beads, you must evaluate them based on the '5S' criteria: Surface, Shape, Size, Shine (Luster), and Shade (Color). For high-end jewelry, prioritize AAA grade pearls with a mirror-like luster and minimal surface blemishes (less than 5%). For mass-market fashion accessories, AA or A grade pearls offer a better balance of cost-efficiency and aesthetic appeal. Always request a cross-section view or X-ray report to verify the nacre thickness, especially for saltwater pearls, to ensure long-term durability.