Last two( I am losing the will to live here )
19d..."State's agent holding up fine diamonds"....SPECIFY
I can see SPY and ICE but I am not sure how this fits the definition of the clue.
26a...if the above is correct than "Drop in price for 9" (8) must be FORMALLY, but again can't quite see it. 9a was PASTA, therefore past as in formally but where does price come into it ?