All is not gold that glisters.

George Herbert (1593–1633) Welsh priest, orator, poet.
Jacula Prudentum, or Outlandish Proverbs, Sentences, &c. (compiler), # 306 (1640 ed.)
    (Source)

Usually modernized as "All that glitters is not gold."

Also recorded in James Howell, Paroimiographia [Παροιμιογραφία]: Proverbs, or, Old Sayed Sawes & Adages, "English Proverbs" (1659) [compiler], in three different places.

See Shakespeare, Tolkien.