All that is gold does not glitter

नारिकेलसमाकारा
दृश्यन्ते हि सुहृज्जनाः ।
अन्ये बदरिकाकारा
बहिरेव मनोहराः ॥

- हितोपदेशः

Good-hearted people seem to be formed like coconuts (hard on the outside, soft and sweet within). Others are like jujube fruits which are attractive only on the outside.

Appearances are deceptive.
All that is gold does not glitter.
Do not judge a book by its cover.