When selecting crystal stones, prioritize the material composition (Lead-glass vs. K9 crystal vs. Acrylic). For high-end garments, K9 glass or Lead-free crystal is preferred for its superior refractive index and clarity. Pay close attention to the facet cutting technology; stones with 12 to 16 facets provide significantly better brilliance. Additionally, verify the back-coating quality (usually silver or gold foiling), as a high-quality vacuum-plated backing prevents peeling and ensures the stone maintains its luster after multiple washes.