The Queen and Prince Philip are set to celebrate their 73rd wedding anniversary next month.
But in the seven decades since they got married, they've kept one closely guarded secret, according to the Daily Mail.
Just like Meghan's and Kate's, the Queen's wedding ring is made from Welsh gold.
What sets it apart is that it's engraved with a secret message chosen by Philip in 1947 -and even those closest to the monarch don't know what it says.
Royal author Ingrid Seward writes in her new book Prince Philip: A Portrait of the Duke of Edinburgh that "Philip didn't have the expense of a wedding ring, as the people of Wales supplied a nugget of Welsh gold from which the ring was made".
"She never takes it off and inside the ring is an inscription.
"No one knows what it says, other than the engraver, the Queen and her husband."
Philip also had her engagement ring made from a tiara that belonged to his mother, Princess Alice of Battenberg.
Photo / Getty
Before he proposed, Philip had the tiara taken apart, and the diamonds repurposed to make a ring for his bride-to-be.
He then designed the three-carat solitaire with five smaller diamonds.
The royals married on November 20, 1947 at Westminster Abbey, with more than 200 million people watching the service on TV from around the world and 2000 guests attending.
The Queen and Prince Philip recently returned from Balmoral. They spent six weeks at their Aberdeenshire home but are now spending some private talk in Norfolk at their Sandringham estate.
This article was first published on the NZ Herald and is republished here with permission.