There's an odd thing in English, that many others have noted but that I've never really seen an explanation of. That is this:

There is an entire class of English words that begin with gl- and have to do with light effects.

We have in English:

Gleam, glitter, gloss, glow, glister, glare, glad, glade, glacial, glass . . .

All these words, and a lot more including gold and yellow, descend from the Proto Indo-European root ghel- 2.

It's an interesting pattern; that root is largely preserved in the gl- beginning of these words; gl- is almost functioning as a morpheme, the smallest possibly unit of meaning in a language. And if you're still scratching your head over how yellow could possibly come from the I.E. *ghel-2, it's because we write yellow with a Y today, but in Old English it was written geolu.

For your amusement, as well as for purposes of verification, I've inclued a few gl- words' etymology from the American Heritage Dictionary. I note that without out counting derived words, like Scots glister instead of glitter, that there are many, many more gl-words derived from Proto Indo-European ghel- and ghel-2.

Glow:
[Middle English glouen, from Old English glowan; see ghel- 2 in Indo-European roots.]

Glitter:
[Middle English gliteren, to sparkle , from Old Norse glitraghel-2 in Indo-European roots.] glit'ter.ing.ly adv. , glit'ter.y adj.

Gleam:
[Middle English glem, from Old English glaem; see ghel-2 in Indo-European roots.]

Glare:
[Middle English glaren, to glitter ; akin to Middle Low German glarenghel-2 in Indo-European roots.]

Gloss:
[Perhaps of Scandinavian origin; akin to Icelandic glossi, a spark; see ghel-2 in Indo-European roots.]

Glacial
[French from Old French, icy , from Latin glaci?lis , from glacies, ice ; see ghel- in Indo-European roots.]

Glad:
[Middle English, from Old English glæd; see ghel-2 in Indo-European roots.]

Glade:
[Middle English, perhaps from glad, bright and shining; see glad 1 .]

Glass:
[Middle English glas, from Old English glæs; see ghel-2 in Indo-European roots.]