A flaw in white jade can still be polished away; a flaw in one's words cannot be taken back.
Tips
usage
The everyday word is 玷污 ('to defile / besmirch'), used for honor, reputation or purity. The literal sense is a spot on a piece of jade; the figurative 'moral stain' sense is far more common today.
On the left this is the jade radical 玉 written as 王 (it loses its dot in left-side position). It marks a jade word — here a flaw in jade, hence a blemish. Same family as 珍 precious and 瑕 jade-flaw.
