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.
The Queen never takes off her wedding ring. Photo / Getty Images
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.
