Shield of Arms of HRH Prince William, Duke of Cambridge (Formerly Prince William of Wales). (born 1982) son of Prince Charles, Prince of Wales and Lady Diana Spencer. The arms was granted in June 2000, on his 18th birthday. The small red ‘escallop’ or sea-shell on the central point alludes to the arms of his mother and the Spencer family. He is the only one of Queen Elizabeth II's grandchild to bear a label of three points (usually reserved only for a child of the Sovereign). [1]
“

Quarterly, 1st and 4th Gules three lions passant guardant in pale Or armed and langued Azure (for England), 2nd quarter Or a lion rampant within a double tressure flory-counter-flory Gules (for Scotland), 3rd quarter Azure a harp Or stringed Argent (for Ireland), with over all a label of three points Argent the central point charged with an Escallop Gules.

”