In 1843 a remarkable and extremely rare 85-page book (only three copies are at present known) was produced by the noted historian, Patrick Fraser Tytler, written "in obedience to the order of the Queen" (Queen Victoria), called Historical Notes on the Lennox or Darnley Jewel; the Property of the Queen. It describes a unique and beautiful sixteenth-century jewel, made in the form of a gold heart and richly enamelled, covered in family symbolism and secret messages. 

The Jewel was made for Margaret Douglas, Countess of Lennox, in memory of her husband, the Regent Lennox. He was of the blood royal of Scotland, his mother having been Lady Anne Stewart, daughter John, Earl of Atholl, brother of James II. Margaret Douglas (born 1516) was of the blood royal of England, her mother having been Lady Margaret Tudor, eldest daughter of Henry VII of England and widow of James IV of Scotland.

 The Darnley Jewel, long kept in the Library at Windsor Castle, is now on show in the excellent new display at the Palace of Holyroodhouse, Edinburgh, where it may be seen when the Palace is open to the public, though it really needs a magnifying glass to appreciate its beauty and complexity properly.