A ton of tanks being the only one from their realms would have already gotten Emerald/Amber void by being on the Rubies if this were the case, as noone else on their 'realm group' would be on those colors.
Nothing to see here.
HOWEVER- this does give me an idea (yes, sorry, I know theres [NO THEORIES] here). You can drop group on the dragons and not be kicked out of the dungeon for several seconds (while mounted/falling), if you drop group at 1% on Eregos.. wonder if it would give the achievements? Noone in your party would be on the drakes, but you wouldnt be in the party for the Eregos kill, either. Might be able to kick some/everyone (not using LFG kick, standard party kick). I've already got Glory of the Hero so I can't try it myself.