The most common myth is that the term arose after the Massacre of Glencoe due to a resemblance in the playing card and Sir John Dalrymple coat of arms. Another myth is that the order for no quarter at the Battle of Culloden written on a nine of diamonds by the Duke of Cumberland.
Other less popular theories include the term deriving from a tax levied to pay for nine diamonds stolen from the crown of Scotland or that the term is a mispronunciation of "The Cross of Scotland" due to a resemblance in the patterns of St. Andrew's Saltire and the playing card.
See also
Categories: Poker gameplay and terminology