All that glitters is not gold

“All that glitters is not gold” is an aphorism stating that not everything that looks precious or true turns out to be so. While early expressions of the idea are known from at least the 12th–13th century, the current saying is derived from a 16th-century line by William Shakespeare:

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All that glitters is not gold

Often have you heard that told.

Many a man his life hath sold

But my outside to behold.

Gilded tombs do worms enfold.

Had you been as wise as bold,

Young in limbs, in judgment old,

Your answer had not been inscrolled

Fare you well. Your suit is cold

_
William Shakespeare_