Where diamonds may be found in store (2,3,5)
I believe the answer is:
on the cards
I believe this clue is a double definition.
'where diamonds may be found' is the first definition.
(as in diamond playing cards)
'in store' is the second definition.
(both can mean expected or imminent)
(Other definitions for on the cards that I've seen before include "Greetings may be" , "a fair certainty" , "to have a PAYE job?" , "place for 6 19 [SEASONALMESSAGES]" , "expected" .)