The decision to propose with Princess Diana’s ring was not spontaneous. Prince William had thought about it for years before the moment in Kenya in October 2010. He had spoken to Princess Catherine about his mother — about who Diana was, what she had meant to him, what the ring represented — long before he placed it on her finger.

“It’s very special to me,” Prince William said of the ring in the engagement interview. “As Kate’s very special to me now, it was right to put the two together.” He described wanting his mother involved in the moment, present in the only way still available to him.
Princess Catherine knew the weight of what she was accepting. She knew the ring’s history — the 1981 wedding, the marriage, the years of documented difficulty, the death. She knew that wearing it would mean carrying all of that, publicly, every day, for the rest of her life. She accepted it without hesitation.
Royal biographer Robert Lacey wrote that Prince William’s decision to give Catherine the ring was understood by both of them as a statement of something larger than engagement — an acknowledgment that Diana’s story was not separate from their story, but part of it.
Princess Catherine has worn the ring every day since October 2010. She has worn it at state banquets and school runs, at Wimbledon and Westminster Abbey, at a coronation and a state funeral. In every context, in every year, the ring is there.
He told her everything. She said yes anyway. The ring has been on her hand every day since. That is the complete story — and it is, in the way the best stories are, entirely sufficient.