flop bet is standard since you could turn equity plus you have overcards the turn could go either way i would lean toward a check/call even check/fold since front door flush and you dont block any diamonds vilian can definetly have Ax type hands with Ad really depending on his sizing and here since you dont block any diamonds
vs. and unknown that called the flop bet, the turn is a check/fold. The turn could be a bet if you were firing all diamonds on the river, but I wouldn't recommend doing this at 2nl vs. and unknown.