All that glitters is not gold

Meaning

Things that look attractive or valuable on the surface may be worthless once you examine them closely. It is a classic warning to be wary of first impressions.

Cautious, sagely

Used in a sentence

• That job offer sounds perfect but remember that all that glitters is not gold.
• Be careful with that flashy website because all that glitters is not gold.
• The car looked beautiful in the photo but all that glitters is not gold.