nem tudo que reluz é ouro

You can use it as a standalone reaction. If a friend shows you a suspicious 'get rich quick' scheme, say it. You can also integrate it into a sentence. Use it to describe people, products, or even job offers. It works best when someone is being overly optimistic about something new. It acts as a gentle, wise piece of advice.

Use it when you are discussing a new relationship that seems too perfect. It is great for business meetings when evaluating a flashy competitor. Use it when shopping for used cars or cheap electronics. It fits perfectly in a heart-to-heart talk about life's disappointments. If you are texting a friend about a 'perfect' influencer, this is your go-to phrase.

Don't use it to describe something that is actually gold. That would just be confusing! Avoid using it in moments of pure, genuine celebration. If your friend just won the lottery, don't ruin the mood. It can sound a bit cynical if overused. Don't use it if you want to be extremely supportive and optimistic. It is a phrase for realists, not for dreamers in the clouds.

This expression is a universal classic with deep European roots. In Brazil and Portugal, it is deeply embedded in the culture of 'malandragem' (street smarts). Portuguese speakers value being 'esperto' (clever). Knowing that appearances lie is a sign of maturity. It has been used in literature and fables for centuries. It reflects a cultural history of being cautious with outsiders and flashy promises.

You might hear people say nem tudo o que reluz é ouro. The 'o' before 'que' is optional but common. Some people might simply say as aparências enganam (appearances deceive). However, the 'gold' version is much more poetic. It is one of those phrases that every single native speaker knows. You will hear it in soap operas and read it in newspapers alike.