[mythrilfox]

it seems like if the turn gets capped and we improve on the river a bet/3bet has a lower chance of succeeding, since leading the river after a flop and turn cap should make a two pair or set pause for concern (even moreso with the running diamonds). but if we just call the turn and donk the river a lot of hands might think we're just trying to prevent a free showdown and raise for value.

edit: sorry i guess this was said already in so many words. but if calling the turn will increase the likelihood a bet/3bet succeeds on a diamond river then i vote for call.