lú huǒ chún qīng

ㄌㄨˊ ㄏㄨㄛˇ ㄔㄨㄣˊ ㄑㄧㄥ

Idiom

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