王 on the left is the jade radical 玉 in compressed left-side form, the bottom dot dropped. It tags 珂 as a precious-stone word, grouping it with 玛 (agate), 珍 (treasure), and 珠 (pearl).
可 supplies the reading, shifting tone from kě to kē. The same phonetic anchors a wide family - 河 (river), 哥 (elder brother), 何 (what) - all hovering around the ke and he syllables.
