This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
礥 combines 石 (stone) with 賢, but the exact historical development and original meaning are uncertain.
The kanji has a stone 石 beside 賢, but its meaning is unclear. Imagine a wise person 賢 puzzling over a difficult stone 石, reflecting the kun-reading むつかしい (difficult).
For キン, picture a wise person 賢 holding a stone 石 and saying it's as precious as kin (gold): kin -> キン.