When Prince William asked for Catherine's hand in marriage, he gifted her with the most iconic symbol of his mother: her engagement ring, a 12-carat oval blue Ceylon sapphire surrounded by 14 diamonds set in 18-carat white gold. The ring has obvious sentimental value to William, and Catherine never makes a public appearance without it.

For their 2011 wedding, William and Catherine chose a very special song to walk down the aisle to: Sir Hubert Parry's anthem "I Was Glad," which was played at Prince Charles and then-Lady Diana's 1981 wedding. The first song sung by their 1,900 guests at Westminster Abbey was "Guide Me, O Thou Great Redeemer," which was the final hymn to be sung at Diana's 1997 funeral and was chosen by William and Prince Harry to be played in the Guards Chapel on the 10th anniversary of Diana's death.

Another nod to Diana? Westminster Abbey, the site of the spectacular nuptials, was also the location of Diana's 1997 funeral.

When Kate appeared on the steps of the Lindo Wing following the birth of Prince George, she was wearing a periwinkle dress with white polka dots by designer Jenny Packham. When Diana introduced Prince William to the world on those very same steps decades earlier, she wore a similar polka-dot dress by Catherine Walker. Both William and George were wrapped in a merino wool christening blanket by British knitwear designer G.H. Hurt & Son, a blanket you can also see in the first photo the couple released of their new family of three.

Rather than have George baptized in the Music Room at Buckingham Palace like Prince William and Prince Charles before him, Catherine chose the Chapel Royal at St. James' Palace for the ceremony — the same location where Princess Diana's body lay for viewing before her funeral at Westminster Abbey.

The most direct reference to Princess Diana occurred when Princess Charlotte's full name was announced: Charlotte Elizabeth Diana. Will and Kate's choice directly referenced the two women who influenced the Prince's life the most, his grandmother, the queen, and his mother.

Rather than baptize Charlotte in London, Kate chose a more quaint location for the ceremony — and one that was a major throwback to William's mother. St. Mary Magdalene Church on the Queen's Sandringham Estate in Norfolk was the very same location of Diana's own baptism so many years before.

Kate rarely dons much bling, and we've seen her in a tiara only three times — one of which was at her own wedding — but the third time was definitely the charm. Last December, she attended the queen's annual diplomatic reception in the Cambridge Lover's Knot tiara, which was Diana's go-to tiara for major occasions.

Some of the most glamorous photos ever taken of Princess Diana were from her favorite photographer, Mario Testino. He even shot her stunning, final spread in Vanity Fair shortly before her death. Kate has chosen Testino for two very special occasions for her own family: her engagement photos and Princess Charlotte's christening.

Diana shocked royal traditionalists when she sent Prince William and Prince Harry to nursery school outside of the palace walls, unlike generations of royals before them. Instead, she chose a Montessori school in west London for her children's first foray into academics. It came as little surprise that Kate also chose a Montessori school for Prince George when it came time for him to enter creche — he now attends one in Norfolk several mornings a week.

It is an image that still lives in infamy: Diana sitting alone, forlornly, on a bench in front of the world's greatest testament to love, the Taj Majal. Now Will and Kate are set to visit the site during their trip to India in April 2016, and will allow photos to be taken of them sitting on "Lady Di's Chair," as tour guides now refer to it.