爐火純青 lú huǒ chún qīng

DEFINITIONS

  1. lit. the stove fire has turned bright green (allusion to Daoist alchemy) (idiom)
  2. fig. (of an art, a technique etc) brought to the point of perfection

CHARACTERS

爐 lú fireplace, stove, oven, furnace
火 huǒ fire, flame; burn; anger, rage
純 chún pure, clean, simple
青 qīng blue, green, black; young