Slamming

Matchpoints again, vulnerable against not, partner held this in third seat:
S void
H QJ9632
D 1043
C Q742

I opened a diamond, left hand opponent passed, and it's her call. What would you bid? You have 2H available as weak.

My partner bid 1H which I like. I think the hand is too good in support of both minors to block them out prematurely. The auction continued quite vigorously:

1D (P) 1H (1S);
3C (3H*) P (4S); *no one asked what this was
5C (5S) ?

Now what? (Feel free to comment on the second round pass too.)

Partner should have at most 3 major suit cards, and that many only if the minors are solid or close to it. It wouldn't be too surprising given your spade void if partner is short in hearts, although certainly the opponents *could* have 12 or 13 spades. It's possible if 6C is down that 5S was making and down 1 is a profitable sacrifice even at these colors. So my partner bid 6C, which I thought was a good bid.

This put fourth seat on the spot with this hand:
S AK10743
H A5
D 9862
C 6

And, unluckily, he believed our bidding and took a sacrifice holding three quick tricks! Which turned out to be correct since I held solid clubs (but for partner's queen) and diamonds and only one heart. +100 was below average although it did beat the -850 from the pair that doubled the making 5S. But worst of all, my diamonds were actually AKQJ7, so if he'd doubled instead, I'd have won two beers (or four, I suppose, depending on how greedy I was).