Gem Finder

http://www.wowgemfinder.com/cut_gems/list/rare
http://wowgems.jponrails.com/cut_gems/list/uncommon

Useful for finding out which gems are best for you for each slot

Any gem will work in any slot, but if you want the socket bonus you need the appropriate colors.
You can send any uncut green gem to Cheve to cut, I can also craft the blue +4 hit, +4 agi and the +5 spell damage +6 stamina also the +strength one i believe.