(John Stillwell/WPA Pool/Getty Images)
Arriving for the event with her husband of one year, Prince William, 30-year-old Middleton had a pin on the lapel of her dress. Richard Palmer, who is the royal reporter for the UK's Daily Express, explained the significance of the jewelry via Twitter, writing: "Kate's wearing a maritime-themed brooch featuring two silver dolphins. It's a gift from the Royal Navy Submarine Service."
William, who had on his Royal Air Force uniform for his grandmother's special day, is the Commodore in Chief of the Royal Navy Submarine Service. Middleton reportedly received the pin as a wedding gift.
Middleton, carrying a tartan scarf, with Prince William (John Stillwell/WPA Pool/Getty Images)
Middleton's vibrant McQueen dress — the same designer that made her wedding gown — has been getting mixed reviews following the outing. While it's clear she wowed the crowd — there were 1.5 million spectators watching the royal family — and looked stunning, some thought she stole some thunder from Queen Elizabeth herself, who was being honored for her 60 years of being on the throne. The honoree was dressed in a more subtle white dress with silver accents.
A year after marrying Prince William, Middleton is starting to take some style risks. Earlier this month while attending an event with William she showed some leg in a white RM by Roland Mouret dress which featured a thigh-high split.
Middleton with Queen Elizabeth and Camilla, Duchess of Cornwall (WPA - David Crump/Getty Images)
The diamond jubilee river pageant honoring the 86-year-old queen featured more than 1,000 vessels -- including gondolas and kayaks — floating down a seven-mile stretch of the River Thames. The entire royal family was in attendance and the event ended with a fireworks display over Tower Bridge. Later, Paul McCartney and Elton John sang for the queen at a picnic held in the gardens of Buckingham Palace. The festivities will come to an end Tuesday with a church service at St. Paul's Cathedral, carriage procession through London, and an appearance by the queen and her family on the balcony at Buckingham Palace.
More Celebrity Features on Yahoo!:
- Angelina Jolie's 5 most fascinating quotes
- Hugh Hefner reunites with his runaway bride!
- 'Real Housewives': Then & Now (Photos)
- Royal Families
- Kate Middleton
- Prince William
- Royal Navy Submarine Service
- Alexander McQueen