When evaluating tourmaline beads, you must prioritize color saturation, clarity, and cut precision. High-quality beads should exhibit vibrant hues (such as Paraiba blue, rubellite red, or chrome green) without significant cloudiness or large internal fractures. Ensure the drill holes are centered and smooth to prevent thread breakage during assembly. For high-end collections, verify the dichroism, where the stone shows different colors from different angles, as this is a hallmark of genuine tourmaline.