红颜易水蓝颜易非
[hóng yán yì shuĭ lán yán yì fēi]
'Beauty fades quickly like water; handsomeness may easily seem false.' This refers to the fleeting nature of physical beauty for women ('red face' meaning woman) and how male beauty ('blue face' meaning man) can appear deceptive, highlighting concerns about appearances being temporary and often unreliable.