Quote Originally Posted by Offhand
We do not know if that is the case. SSC/TK were launched with TBC and they contained t5. Ulduar was not launched with Wrath (which is the only instance to date to contain t8 level stuff). We don't know the level of difficulty the Argent Colosseum will be. It could be like ZA, with a timed-event challenge/special mount, etc. OR, it could be a new level of content. Neither is confirmed.

And nothing says gem stat ratios have remained constant from TBC to Wrath. A pattern of one example is not a pattern at all.

EDIT: I would certainly like epic gems, but no where are they a guarantee. Seeing as Blizzard is dead set on balancing professions to be exactly equal at all times, it wouldn't be surprising at all to see +3 points of stat added to JC gems once epics are introduced.
A note on epic gems that people forget - we know that there are epic-quality wrath gems in game, at 30 stamina/equivalent(http://www.wowhead.com/?item=40119 etc.). Thus, we know that the gem quality ratios are the same from BC to wrath in all cases. That said though, colliseum could easily be something like ZA/AQ40, which IMO is quite likely, and so I'm not expecting epic gems until icecrown.