[xwowsersx]

I think unless you know your opponent to be making razor thin value bets or bluffs, you sort of have to fold this turn. In general, against an unknown you cant be looking to get too deep in the hand on a three to the flush board when you have none of that suit. Also, keep in mind he could have QJ. So I think you should really be folding this turn. You don't know where you stand in the hand and you have no diamonds.