The 630 watt ceramic metal halide is made of arc tube shell with polycrystalline alumina ceramics which is a translucent material. In fact, its transmittance is as high as 96-98%, which is higher than glass and quartz. But because the linear transmittance is not more than 30%, it becomes translucent. This kind of ceramic material can withstand high temperature over 200℃ higher than quartz. The normal operating temperature after making arc tube can be as high as 1200 C, and its thermal conductivity is higher. The temperature distribution of arc tube itself is more uniform, even at the cold end, it is above 900 ℃. Therefore, the metal halide filled in it can evaporate sufficiently, which is the reason for the high and stable light efficiency and color rendering index of 630 watt ceramic metal halide. The ceramic bulb shell of 630 watt ceramic metal halide has high thermal and chemical stability and it does not react with the material filled with arc tube, and there is no sodium leakage problem. Therefore, the lamp has stable performance, low light decay and long life. The biggest advantage is that the luminous efficiency is very high, and the luminous efficiency is as high as 80-90 Lm/W, and the heat is less when the normal luminescence occurs, so it is a kind of cold light source.