I had thought that “Emerald Tablet” would be “Tábla Smaragaide,” Smaragaide referring to an actual emerald. I just put that out there to have something to work with. %-P
The main thing that was confusing me was how one would convey “Emerald Green.” For example:

[url=http://www.irishdictionary.ie/dictionary?language=irish&toLanguage=english&word=smaragaide]Here[/url] it’s “Glas Smaragaide.”

[url=http://talkirish.com/forums/p/2856/7337.aspx]Here[/url] somebody says that “Smaragaidghlas” is an acceptable construction.

And, of course, you have Oileán Iathghlas na hÉireann as “The Emerald Isle.”

Go raibh maith agat for explaining the “Iath” part! I couldn’t find that anywhere in my (one) dictionary.
Any other information would be appreciated!
Go raibh maith agat, arís!