點睛之筆 [点－－笔]

Jyutping dim2 zing1 zi1 bat1
Pinyin diǎn jīng zhī bǐ

Definitions (CC-CEDICT)
  1. the brush stroke that dots in the eyes (idiom); fig. to add the vital finishing touch
  2. the crucial point that brings the subject to life
  3. a few words to clinch the point
Definitions (Wiktionary)
  1. phrase, idiomatic
    the finishing touch to a painting; the crucial point that brings the subject to life