Right
圭 supplies the sound — guī drifted to jiā, an irregular but historically attested shift.
圭 is a ceremonial jade tablet (two
土 stacked, an etched stone of rank), so the right side also faintly suggests preciousness — fitting for a 'fine' person. Same phonetic family:
街 (jiē, street),
蛙 (wā, frog),
挂 (guà, hang).