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Diamond Blackjack



Diamond Blackjack is a blackjack game created by Gamesys N.V., a provider of software for Internet casinos. The game could most closely be compared to Super Fun 21, but there are enough rule differences to make it worthy of its own page.



Conventional blackjack rules are followed, with these specifics:

  1. Six decks
  2. Dealer stands on soft 17.
  3. No hole card. Player loses total amount bet if dealer gets blackjack.
  4. Player blackjack is an automatic winner.
  5. A blackjack in diamonds pays 2 to 1. All other blackjacks pay 1 to 1.
  6. Player may double on any number of cards, including after splitting.
  7. Player may surrender at any time, including after splitting.
  8. Player may re-split to four hands, including aces.
  9. Draw to split aces not allowed.



The following table shows the basic strategy.


The player should surrender after doubling, known as "double down rescue," as follows:

  • Surrender 16 or less against an 8, 9, 10, or ace.
  • Surrender 17 against an ace.



According to my analysis, the house edge in Diamond Blackjack is 1.24%.

Side Bets


There are two side bets, as follows.

The first is simply on a player blackjack and pays 19 to 1. The probability of winning is 4.75% and the house edge is 5.02%.

The second is titled "Sevens" and pays according to the number of consecutive sevens the player gets. The sevens must start with the first card. Splitting two sevens will pay as two sevens, regardless of the next card. The following table shows the the probability and return of each event. The lower right cell shows a house edge of 4.09%.

The table assumes the player will always hit two sevens and does not consider the cost of deviating from basic strategy by doing so against a dealer 2 to 7, when the player should split.


Event Pays Permutations Probability Return
Three sevens 250 12,144 0.000404 0.100931
Two sevens 40 158,976 0.005285 0.211405
One seven 8 2,142,720 0.071234 0.569874
No sevens -1 27,766,080 0.923077 -0.923077
Total   30,079,920 1.000000 -0.040867

Zero House Edge


There is also a so-called "Zero House Edge" version of the game. The only difference is in how much a blackjack pays, which is as follows:

  • Ace-king in diamonds pays 7.5 to 1.
  • All other diamond blackjacks pay 4 to 1.
  • All other blackjacks pay 1 to 1.

The average blackjack pays 1.2422 to one.

According to my analysis, the house edge in the "zero house edge" version is 0.39%.

External Links


Diamond Blackjack rules at BetVoyager.com.