Their engagement became official on 24 February 1981, after Lady Diana selected a large engagement ring consisting of 14 solitaire diamonds surrounding a 12-carat oval blue Ceylon sapphire set in 18-carat white gold, similar to her mother's engagement ring. The ring was made by Crown jewellers Garrard. Unusually for a royal engagement ring, the ring was not a custom-made design and was at the time featured in Garrard's jewellery catalogue available to the public. In 2010 the ring became the engagement ring of Catherine, Duchess of Cambridge. It was copied by jewellers all over the world.
Following the engagement Lady Diana left her job at the kindergarten and moved to Clarence House, then home of Queen Mother, for a few days. Diana lived at Buckingham Palace for most of this pre-wedding period. Her first public appearance with Prince Charles was a poetry reading on March 9, 1981 at Goldsmiths' Hall where she met Princess Grace of Monaco.
Twenty-year-old Diana became Princess of Wales when she married the Prince of Wales on 29 July 1981 at St Paul's Cathedral, which offered more seating than Westminster Abbey, generally used for royal nuptials. It was widely billed as a "fairytale wedding", watched by a global television audience of 750 million while 600,000 people lined the streets to catch a glimpse of Diana en route to the ceremony. She was the first Englishwoman to marry the heir to the throne for 300 years (when Anne Hyde married the future James II from whom Diana was descended).
At the altar, Diana accidentally reversed the order of Charles's first two names, saying "Philip Charles" Arthur George instead. The word "obey" was omitted from the wedding vows at the couple's request, which caused some comment at the time. Diana wore a dress valued at £9000 with a 25-foot (7.62-metre) train. Music and songs used during the wedding included the "Prince of Denmark's March", "I Vow to Thee, My Country", "Pomp and Circumstance No.4" and the British National Anthem.
The Prince and Princess of Wales spent the first night of their honeymoon at the Mountbatten family home at Broadlands, Hampshire, before flying to Gibraltar to join the Royal Yacht HMY Britannia for a 12-day cruise through the Mediterranean to Egypt.They also visited Tunisia, Sardinia and Greece. They finished their honeymoon with a stay at Balmoral.