However, to produce sparkling, flawless crystal requires raw materials of very high purity. Moreover, the furnace must be kept at a constant temperature and there can be no impurities in the melting stage.
然而，要使玻璃晶瑩剔透、完美無瑕，必須要使用高純度的原料，並在混合融熔的過程中保持均溫、沒有雜質。