gem, precious stone, jade
琦 centers on a precious, beautiful stone: a gem, especially jade. It refers to something rare and valuable in a literal mineral sense.
琦 combines 王 (jade) with 奇, which likely contributes the sound and the idea of something unusual or extraordinary, together suggesting a rare, precious stone.
The left side 王 (jade) tells you it's a precious stone, and the right side 奇 (strange/unusual) hints that it's an extraordinary gem. Picture a strange, rare jade stone that stands out from all others.
For キ, imagine a key made of jade: key -> キ, and this precious stone key unlocks a treasure chest of gems.