Most fine crystal contains lead oxide. 24% is the optimum percentage for color, weight and hardness, while still ensuring clarity, sparkle and brilliance. 24% Lead Crystal, with its exceptionally high perceived value, has been sought after and treasured for generations, and remains a status symbol even today. The presence of lead also makes the glass softer and easier to cut. Crystal can consist of up to 33% lead, at which point it has the most sparkle.