Kurt Hummel's so bright I gotta wear shades

Since encountering the word "glasz" for the first time last week while perusing fan fiction, and after failing to find it in the Merriam-Webster or the Shorter Oxford English Dictionary, I've been curious about the etymology.

I went to the university library today and it occurred to me that it would almost certainly have the complete Oxford English Dictionary (OED) on hand. If you're not familiar with the OED and you are interested in words, you really need to become acquainted. With more than 616,000 entries, it is the most comprehensive dictionary of the English language. Plus, each entry includes a reliable history of the origins of each word, and often notes on similar words in related languages.

So I asked my reference librarian to point me to the OED. As much as I love big, fat 20+ volume books, I opted for the online version because it is updated more frequently, and I suspected that glasz is a neologism.

Alas, glasz is so new that it's not in the online OED. I felt a bit defeated, but then I decided to look up cerulean, which is my other recent obsession. And there, in the etymological notes for cerulean was a reference to the Welsh word glas:

Latin cærule-us dark blue, dark green, applied to the sky, the sea (Mediterranean), but occas. to leaves, fields: compare Welsh glas. In the mod. languages always taken as deep blue.

I kind of want to fault the OED here for not being absolutely clear on why it's pulling out the Welsh glas here, but I think it's safe to assume that it's implying that cerulean and glas share an Indo-European root. (Also, I'm a little annoyed that OED says cerulean is always taken as deep blue, but that's just because I don't want it to be so.)

Anyway, I looked up glas in the Welsh-English dictionary of the University of Wales Trinity Saint David, and this is what I got:

1. sky n. blue adj. pale adj. grey adj. green adj. young adj. raw adj.

So, finally, I understand why people are using the word glasz to describe Kurt's eyes. What I don't understand is why they spell it that way. If I ever end up using it, I'll probably keep the Welsh spelling and italicize it, just like when I use non-naturalized French words in my writing. But I doubt I'll ever use it, unless Kurt or Blaine end up going to Wales, or Kurt turns out to have a Welsh relative I haven't met yet. Because I just don't see it coming up naturally for them, otherwise.