Where does “kol” come from?

kol (Norwegian Bokmål) comes from Old Norse kol, from Proto-Germanic kulą, from Proto-Indo-European gʷol-, from Proto-Indo-European ǵwelH- — to burn; to shine.

Ancestry of “kol”, step by step

Step	Language	Word	Meaning
1	Old Norse	kol	coal
2	Proto-Germanic	kulą	coal
3	Proto-Indo-European	gʷol-	—
4	Proto-Indo-European	ǵwelH-	to burn; to shine

Every word from Proto-Indo-European ǵwelH- →Every word from Proto-Indo-European gʷol- →Every word from Proto-Germanic kulą →