Prince Williamd and Kate Middleton
Prince William doesn't like jewelry so he doesn't wear his wedding ring despite wife Kate Middleton wearing hers. Pictured: Prince William and Middleton pose for the official tour portrait for their trip to Canada and California in the Garden's of Clarence House on June 3, 2011 in London. Getty Images/Chris Jackson

Prince William and Kate Middleton may have been happily married for six years already, but the former doesn't wear his wedding band.

For those wondering why the Duke of Cambridge doesn't wear his wedding ring when his wife sports hers, the explanation is very simple, according to one royal insider: Prince William is not fond of jewelry. "He doesn't like jewelry, and the Palace issued a statement before their wedding saying so," Penny Junor told Vogue.

"[Not wearing his wedding ring is] his prerogative," said Robert Jobson, royal editor of London's Evening Standard.

In addition, despite the lack of a wedding band, most are already aware of Prince William's marital status as an estimated two billion people watched his royal wedding with Middleton back in 2011.

On the other hand, Prince Charles wears his wedding ring for both of his marriages, the first to Princess Diana and the current one with Camilla Parker-Bowles. But unlike most men, he wears his discreetly on his pinky finger, next to his signet ring.

It might be surprising for some that Prince William, a contemporary royal, doesn't wear a ring when most married English men today do, including his dad. But for Diane Clehane, author of "Imagining Diana," his choice might be the "most modern thing of all."

"William and Kate have shown us they are modern royals and are confident in each other’s love for one another," Clehane explained. "Kate omitted the word ‘obey’ in her wedding vows, and William has opted not to wear a ring, which makes them like many millennial couples—intent on doing things their way."

In related news, the Duke and Duchess of Cambridge are expecting their third royal baby. The couple confirmed that their next bundle of joy is arriving in April. Middleton had been on a bed rest last month, but she is now back to doing her royal duties.

Last Monday, the royal couple was spotted at the Paddington Station in London for a charity event. Middleton danced with Paddington Bear during the gathering as Prince William laughed and watched them from the side.

Two days later, Prince William, Middleton and Prince Harry visited the London Stadium for the We Are Coach Core event, where the royal trio met future coaches. "For me, getting kids doing sport instead of sitting in front of computers is great. We need to do more of this stuff to get people active," Mark Noble said about the event.