Peter's and Misho's post about the quality of the diamond suit is a point well taken. Yzerman posted here a long time ago a reasonable requirement for a 2 over 1 response being a "biddable" suit. His definition of "biddable" was a suit that CAN be playable opposite 3 small for 2 losers assuming 3/2 break in suit ("Hence Qxxxx is not biddable, Q10xxx is biddable"). This was part of a very nice thread discussing DC Standards potentially artificial 2C response which is GF but may or may not include clubs (see
http://forums.bridgebase.com/in...t=msg322#msg322
So in general, a 2/1 response minimum requirements might best be described as:
These included:
[*] Five card or longer suit, QTxxx or better
[*] Enough HCP to insure game
Now, in the world of 2/1 bridge, people use a lot of different requirements. Some make 2/1 in four card suit with fit planning to raise later, and others even advocate in three card suit. My requirement is a five card suit, unless playing something like this artificial 2C bid.
When lacking a "good enough" suit, for 2/1 GF but with enough values, Yzerman and many ohters adopt an artificial GF 2C, that may or may not include clubs. In fact, it could include short clubs and 5 in diamonds or the other major if those suits or Qxxxx or worse. So here he would respond 2C. If his partner bids 2D he will bid 3D to "establish" diamonds as trumps, and if partner can cue-bid clubs, or shows a club stopper, he will then use minorwood to determine if "6D is playable", but of course, he will end up playing in hearts. (no need to ask in hearts, as the trump queen should fall if partner lacks it and am looking at HEART AK). Imagine...
1H 2C
2D 3D
3N 4D (minor wood)
4H 4S (4H = 0-3 key cards. DAK + CA)
7H Pass
I generally adopt the same rules governing a 2/1 about the quality of the suit (QTxxx or better). But with a huge fit for openers first suit, as in this case, I feel free to relax the requirement. The reason being, there is no way I will ever play this hand in diamonds (unless partner psyched 1H and passes 2D). So the requirement that the suit MIGHT be playable opposite xxx for 2 losers with a 3/2 split is not quite as critical (but partner with three small will be shocked if we lose three tricks in this suit). But playing in hearts EVEN IF my suit was QJT98, we could lose 3 tricks in this suit opposite xxx via a ruff after AK.
But imagine the auction goes...
1H 2D
3D 3H
4C 4N
?
Now 4NT is 6 card RKC (AK of both red suits) and responses show key cards and red queens. So over 4NT
5C = 0 or 3 keys (out of six)
5D = 1 or 4 keys (out of six)
5H = 2 keys, neither red queen
5S = 2 keys, One Queen
5N = 2keys, both queens
Now, change my hand a bit, make it:
S: A
H: AKJXX
D: JXXXX
C: QJ
I would not even consider bidding 2D. Here 2NT seems clearly more appropriate. An advantage to 2NT is that you can find out if your parnter has a singleton diamond. Such a holding would get you merrily on your way to slam. IF you bid 2D, your partner will not be so willing to show a singleton diamond via cue-bid.