monkey in silk

In English: A monkey in silk is a monkey no less. -- No matter how someone dresses, it's the same person underneath.

Equivalent: Don't judge a book by its cover.

In Spanish: Aunque la mona se vista de seda, mona queda.

In Italian: L'abito non fa il monaco. -- Clothes does not make the monk. -- The apparence does not always say the truth about a person. =It is not the beard that makes the philosopher/All Stuarts are not sib (=related) to the King/You can’t judge a book by its cover.

In Polish: Nie szata zdobi czlowieka lecz czlowiek szate. -- Clothes do not make a man look better, but it's a man who makes clothes look good on him. = The clothes you wear are not important but your internal values are (personality, intelligence etc.)