If the flop is q67 with two diamonds and you have qj and the turn brings a queen, you now have trips (and are most probably ahead here).
Villain's pot bet means that he has either two pairs (the 6-7) or an overpair and wants to price out any drawing to the flush. He could also be on a flush draw (but not on the nut flush draw) and tried to represent strength in this spot to take it down. Without any indication of the action preflop (or the type of game, the limits, etc.), it's hard to make a decision.
Anyway, I would bet around 180-200 into that pot in order to not give favorable
odds for the boat and flush draws and would probably do the same thing on the river if no diamonds came up. If I get raised on the turn, I'd reconsider my options: maybe he has a better quicker and the other queen, who knows, but I doubt it.