King Charles's nephew, Peter Phillips, is now engaged to Harriet Sperling, and according to an expert, their engagement ring is quite special.

Peter Phillips, the son of Britain’s Princess Anne and eldest grandchild of the late Queen Elizabeth II, announced his engagement to nurse Harriet Sperling on Friday.

“Mr. Peter Phillips, the son of HRH The Princess Royal and Captain Mark Phillips, and Ms. Harriet Sperling, daughter of the late Mr. Rupert Sanders and Mrs. Mary Sanders of Gloucestershire, have today confirmed their official engagement,” the couple’s spokesperson said in a statement shared with PEOPLE.