K9 crystal is also called K9 glass (also refers to glass products made of K9 material). It belongs to optical glass and is mainly used in optical coating and other fields. Transmittance, refractive effect, hardness and texture are much higher than resin materials. The price per kilogram is 20-40 yuan (for reference only, there is a certain big difference according to different grades). Molding mainly consists of cutting and polishing and press casting (requires furnace). K9 material belongs to optical glass and is crystal clear. Therefore, many factories that process K9 materials have been derived. The products they process are called crystal glass products on the market.