Scoring: IMP
Opponents silent, partner opens, playing 12-14nt
1♦ - 2♣ (GF)
2♦ - 2♠
2NT - 3♣
3NT - ?
<edited after Justin's post>
2♣ being GF is the extent of your discussion about 1♦ - 2♣ auctions.
What is your call? In particular, do you think 4♦ suggests diamonds could be the right strain, or is it a cue for clubs?