[quote=@Vandy]
Could you explain what you mean by magic ring as I thought the Guardians created all the green rings?
[/quote]

That's cute >< Sorry. 
The original ring by Alan Scott wasn't Alien in origin. It didn't come from Oa, but rather Magic. It was weak against wood [s]and yellow things? I'm kind of sketchy on that point.[/s] And his power pretty much derived from "earth and green things". Even though he does (but doesn't later on) use a lantern.