Sounds good. Jewelcrafting can make some good gold. You can also take other people's gems off the AH, cut them, and then put them back up for more gold. Which I think is partially what Jay was doing.
Though you'll have to put in some decent effort to get the plans/recipe's to make those gems. As you won't really get anything that great from the trainer alone. You'll have to do heroics, where they'll either drop or you can buy them from a vendor with the badges you get for killing bosses and completing dungeons. Some even require PvP.