大醇小疵

dàchúnxiǎocī
  1. great despite minor blemishes
  2. a rough diamond

CEDICT

sound on the whole though defective in details

Wiktionary

大体完美而略有小缺点。

重編國語辭典

Entry Composition

1 大 dà
  1. big; large; great
  2. older (than another person)
  3. eldest (as in 大姐 dàjiě)
  4. greatly; freely; fully
  5. (dialect) father
  6. (dialect) uncle (father's brother)
=2 醇 chún
  1. alcohol
  2. wine with high alcohol content
  3. rich
  4. pure
  5. good wine
  6. sterols
=2 醇 chún old variant of 醇 chún
3 小 xiǎo
  1. small
  2. tiny
  3. few
  4. young
4 疵 cī
  1. blemish
  2. flaw
  3. defect