Jacoby transfers show a five-card suit and are used for the majors: 2♦ is a transfer to hearts, 2♥ is a transfer to spades. Opener MUST accept the transfer though he can jump to the three level with 17 points and four-card support for responder's major. (Note: Do not use with exactly 4 cards in other major. In that case, use Stayman.) For example:
| 1NT | 2♦ | |
| 2♥ | Normal acceptance of the transfer | |
| 3♥ | 17 points and four-card heart support |
If, after the transfer is accepted, responder bids a new suit, that is natural and game forcing (except for 1NT-2♦-2♥-2♠ which is not). Possible calls after the accepted transfer are:
| 1NT | 2♥ | |
| 2♠ | Pass | content to play 2♠ |
| 2NT | Invitational. Over 2NT opener can pass or return to 3♠ with a minimum hand; bid 3NT or 4♠ with a maximum | |
| 3♣, 3♦, 3♥ | Natural and game forcing. Shows 5 cards if other major. If minor, often slam try | |
| 3♠ | Invitational | |
| 3NT | Asking for a choice between 3NT and 4♠ | |
| 4♠ | Placing the contract, with a six-card or longer suit |
A 2♠ response requires the 1NT bidder to rebid 3♣, which can be passed with a no game interest and long clubs, or responder can rebid 3♦ with a no game interest and long diamonds. Example:
| 1NT | 2♠ | |
| 3♣ | Pass | Weak with clubs |
| 3♦ | Weak with diamonds |
Other responses to 1NT:
| 1NT | 3♣, 3♦ | Invitational to 3NT with a six-card or longer suit |
| 3♥, 3♠ | At least a six-card suit and slam interest (otherwise responder uses a transfer bid). | |
| 4♣ | Gerber, asking for aces. 4♣ IS GERBER OVER ANY 1NT OR 2NT BID BY PARTNER INCLUDING A REBID OF 1NT or 2NT. Responses show the number of aces, by steps, just as over a Blackwood 4NT. (5♣ is used to ask for kings.) |
| Ace Asking | King Asking | ||||
| 1NT | 4♣ | 1NT | 4♣ | ||
| 4x | 5♣ | ||||
| 4♦ | 0 or 4 aces | 5♦ | 0 or 4 kings | ||
| 4♥ | 1 ace | 5♥ | 1 king | ||
| 4♠ | 2 aces | 5♠ | 2 kings | ||
| 4NT | 3 aces | 5NT | 3 kings | ||
If the player using Gerber makes any bid other than 5♣, that is to play (including 4NT).
A direct raise of 1NT to 4NT is natural and invites 6NT. 4NT is slam invitational only because 4♣ is available as Gerber.
*It is a moot point whether responder's rebid in a minor promises a four-card major. I tend to think that it does not since responder has no other way of making a slam try in a minor.
** The original text said "other major" not "a major". However after opener bids a major it is normal to raise that major with a fit. It is more common to bid a major after opener has rebid 2♦ after Stayman. In this case responder with 5-4 in the majors bids the five-card major at the 2-level with a weak hand and at the three-level with a game-forcing hand. We saw above that a 2♥ rebid by responder can also be made on a weak hand with two 4-card majors that is unsuitable for playing in 2♦.
Some players use the Smolen convention with a strong hand with 5-4 either way in the majors. The Smolen convention reverses the meaning of 3Major over 2♦ so that 3♥ shows five spades and 3♠ shows five hearts. The purpose of this is to achieve a transfer affect so that the stronger hand declares if there is a major fit.
Other rebids by responder in a major after opener shows a major are best played as slam tries with a fit for opener's major.
Some players use the Smolen convention with a strong hand with 5-4 either way in the majors. The Smolen convention reverses the meaning of 3Major over 2♦ so that 3♥ shows five spades and 3♠ shows five hearts. The purpose of this is to achieve a transfer affect so that the stronger hand declares if there is a major fit.
Other rebids by responder in a major after opener shows a major are best played as slam tries with a fit for opener's major.
| 1NT | 2♣ | |
| 2♥ | 3♠ | Slam try - spade cue-bid with heart support |
