With my long-suffering partner we would get to 6S easily enough. A grand would be a not unreasonable gamble at best, and might be bid if we need a swing. But you see, a 41 spade split more or less dooms all grands. And if the fifth diamond and a heart ruff are needed to get to 13 tricks, a club lead will knock of the dearly needed late entry. We don't have the tools to diagnose the importance of DJ. Obviously that would be taken into account in those cases, where a swing is needed, but you only bid a grand when you can count 13 tricks.

Our bidding (approximate, I will actually show this hand to my partner is there are points of interest)

• N:1D (=usually five for we open most balanced hands eithe 1C or an appropriate number of NT), S:1S.
• N:1NT (a Gazzilli variant for showing various hand types), S:2C = a non-minimum hand (8+HCP).
• N:2S (=17+points with exactly 3 card support, 2H would also show 3 card support but a slightly weaker hand, 2D would show 45 in the reds, deny 3 card support, and limit the hand to less than reverse range). Together with South's 2C this creates a game force. S:3S (=sets spades as trumps, so promises at least five, invites cue bidding, so slam positive as opposed to a fast arrival 4S).
• N:4C, S: 4H (lowest controls).
• At this point North should fire Ole Black. The HK just got better (unlikely that partner's 4H is showing a stiff), and there is the chunky diamond suit. N: 4NT, S: 5C, 0/3 out of five, now obviously three, making North sit up.

Three keycards in the South hand is great news. Still, entries for heart ruffs may be difficult to arrange. A diamond jack or king of clubs could do. A probe for a grand is justified, and my partner would probably do one. If my glass has been half empty all evening I might simply close shop at 6S, and apologize if a grand is cold. As others pointed out, longer spades in partner's hand improve the odds for the grand immensely. Then again, a heart ruff may not be needed. I guess a generic king ask/grand invitation is best, so

• N: 5NT, S: 6S (no kings to tell about, nothing extra, that diamond jack is of uncertain value even though you like it).

With my long-suffering partner we would get to 6S easily enough. A grand would be a not unreasonable gamble at best, and might be bid if we need a swing. But you see, a 41 spade split more or less dooms all grands. And if the fifth diamond and a heart ruff are needed to get to 13 tricks, a club lead will knock of the dearly needed late entry. We don't have the tools to diagnose the importance of DJ. Obviously that would be taken into account in those cases, where a swing is needed, but normally you only bid a grand when you can count 13 tricks.

Our bidding (approximate, I will actually show this hand to my partner if there are points of interest)

• N:1D (=usually five for we open most balanced hands either 1C or an appropriate number of NT), S:1S.
• N:1NT (a Gazzilli variant for showing various hand types), S:2C = a non-minimum hand (8+HCP).
• N:2S (=17+points with exactly 3 card support, 2H would also show 3 card support but a slightly weaker hand, 2D would show 45 in the reds, deny 3 card support, and limit the hand to less than reverse range). Together with South's 2C this creates a game force. S:3S (=sets spades as trumps, so promises at least five, invites cue bidding, so slam positive as opposed to a fast arrival 4S).
• N:4C, S: 4H (lowest controls).
• At this point North should fire Ole Black. The HK just got better (unlikely that partner's 4H is showing a stiff), and there is the chunky diamond suit. N: 4NT, S: 5C, 0/3 out of five, now obviously three, making North sit up.

Three keycards in the South hand is great news. Still, entries for heart ruffs may be difficult to arrange. A diamond jack or king of clubs could do. A probe for a grand is justified, and my partner would probably do one. If my glass has been half empty all evening I might simply close shop at 6S, and apologize if a grand is cold. As others pointed out, longer spades in partner's hand improve the odds for the grand immensely. Then again, a heart ruff may not be needed. I guess a generic king ask/grand invitation is best, so

• N: 5NT, S: 6S (no kings to tell about, nothing extra, that diamond jack is of uncertain value even though you like it).