Definition
This idiom suggests that appearances can be deceptive; something that looks attractive or valuable may not actually be so upon closer inspection.
金玉其外，敗紐其中
The restaurant looked great, but the food was actually quite mediocre; it just goes to show that all that glitters is not gold.
這家餐廳看起來很棒，但食物其實很普通；這正說明閃閃發光的未必是金子。
His new car looked luxurious, but it had many problems; it goes to show that all that glitters is not gold.
他的新車看起來很豪華，但有很多問題；這正說明閃閃發光的未必是金子。
That investment opportunity looked promising, but after careful study, it turned out to be very risky; it truly proves that all that glitters is not gold.
那個投資機會看起來很有前景，但仔細研究後發現風險很高；這真正證明了閃閃發光的未必是金子。