Before making any decision you must think about the complete hand.
To make the contract you not only need to avoid 2 diamond losers, but also need the spade finesse to be right. In other words, you need West to hold ♠ K.
If West has ♠ K and ♣ KQ (which is known from the opening lead), West can’t have ♦ A otherwise he would have opened the bidding holding at least 12 points.
In order to make the hand you need West to hold ♠ K and, if so, West can’t also hold ♦ A.
The solution is to play ♦ K and hope all is well.
WHEN YOU NEED A PARTICULAR CARD IN A PARTICULAR HAND IN ORDER TO MAKE A CONTRACT, ASSUME IT IS THERE.
CHECK THE NUMBER OF POINTS ALREADY SHOWN BY A PASSED HAND WHEN FACED WITH WHAT SEEMS LIKE A GUESS.