We've just reviewed "Source of Tricks" suits in class and this hand comes up at Soledad: ♠3 ♥AKQJ9432 ♦A96 ♣4
Your partner opens the bidding 1♦. The ONLY thing you care about is how many Aces and Kings partner has.
IF you have agreed that a jump to 4NT is straight Blackwood, do it. If, for this partnership, a jump to 4NT would be asking for Key cards in diamonds, temporize with one heart. If you bid 1♥; partner will jump to 2♠. Now bid 3♣ and partner will bid 3NT. Depending on your partnership, either 4♣ (my class) or 5♣ is Gerber at this point. Partner will show you two Aces and two Kings.
At this point, you can count 13 tricks!!!
YOU ARE KNOWN TO HAVE eight HEART TRICKS. (Partner MIGHT have a singleton, but does not have a void on this auction, so no one has five hearts to the ♥10. three more Aces takes you to 11 tricks. Two more Kings takes you to 13 tricks. Bid 7NT.
When you can count to 13, put the contract in NT for two reasons: 1) it is more matchpoints; 2) you eliminate the (usually negligible—but not zero) possibility of a ruff on the opening lead.
The sad tale at Soledad is: this board was played 19 times (a web movement).
4 pairs were not even in small slam.
1 pair was in 6♥ and only made 6 (unless it was scored incorrectly)
7 pairs were in 6♥ and made 7.
2 pairs were in 7♥ and made 7.
ONLY FOUR PAIRS WERE IN 7NT (making seven, of course).