flaw, blemish
瑕 centers on a small imperfection that mars an otherwise good surface or object: a flaw or blemish.
瑕 combines 王 (jewel) with 叚, which likely contributes the sound. The character originally referred to a flaw in jade, later extending to any blemish.
The left side 王 (jewel) suggests something precious, while the right side 叚 looks like a crack or mark. Picture a beautiful gem with a tiny visible flaw.
For カ, imagine a car with a small scratch: car -> カ, and that scratch is the flaw on the otherwise perfect vehicle.
flaw; defect; fault
stigmatized property; real estate where a crime, death, etc. has occurred
fly in the ointment; small flaw in otherwise perfect object; only trouble; only fault
scratch; chip; nick
warranty against defects
warranty against defects
blemish; flaw; defect