Selecting a reliable factory requires evaluating their material purity, molding precision, and surface treatment capabilities. Prioritize manufacturers that use Super Flint Glass (Crystal White Glass) for maximum clarity and brilliance. Ensure the factory holds ISO 9001 certification and has a dedicated QC department to check for bubbles, scratches, or uneven glass distribution. For high-end brands, verify if they offer in-house decoration services like silk-screen printing, hot stamping, frosting, or electroplating to ensure design consistency.