Brewer's: Curse of Scotland
The nine of diamonds. The two most plausible suggestions are these: (1) The nine of diamonds in the game of Pope Joan is called the Pope, the Antichrist of the Scotch reformers. (2) In the game of comette, introduced by Queen Mary, it is the great winning card, and the game was the curse of Scotland because it was the ruin of so many families.
Other suggestions are these. (3) The word “curse” is a corruption of cross, and the nine of diamonds is so arranged as to form a St. Andrew's Cross; but as the nine of hearts would do as well, this explanation must be abandoned. (4) Some say it was the card on which the “Butcher Duke” wrote his cruel order after the Battle of Culloden; but the term must have been in vogue at the period, as the ladies nicknamed Justice-Clerk Ormistone “The Nine of Diamonds” (1715). (5). Similarly, we must reject the suggestion that it refers to the arms of Dalrymple, Earl of Stair—viz. or, on a saltire azure, nine lozenges of the first. The earl was justly held in abhorrence for the massacre of Glencoe; so also was Colonel Packer, who attended Charles I. on the scaffold, and had for his arms “gules a cross lozengy or.”
Grose says of the nine of diamonds: “Diamonds ... imply royalty ... and every ninth King of Scotland has been observed for many ages to be a tyrant and a curse to the country.” —Tour Thro' Scotland, 1789.
It is a pity that Grose does not give the names of these kings. Malcolm III. was assassinated in 1046 by Macbeth, William was taken prisoner by Henry II. (died 1214), James I. was assassinated in 1437.