It is assumed that is an eternity ring gifted by Prince William when their first baby, Prince George, six, was born.
They mentioned: “The third ring she wears is an eternity ring. Eternity rings are sometimes used to mark particular milestones in a relationship – on this case, it was a present from her husband to mark the start of their first baby, Prince George.
“Made from 18ct white gold, it options 0.23ct of white diamonds. Kate’s eternity band comes from London-based designer Annoushka, and is valued at £1,200.”
Why does Kate put on three rings on her wedding ceremony finger?
The royal was reportedly given all the rings by Prince William and so they all have nice significance.