Kate Middleton
Kate Middleton arrives to launch a new national support line at the charity Family Action on Jan. 22, 2019 in Lewisham, England.  Getty Images/Adrian Dennis

Prince William surprised Kate Middleton with a stunning blue sapphire engagement ring when he asked for her hand in marriage in 2010. The couple tied the knot months later.

But after the Duchess of Cambridge received the stunning piece of jewelry, the media and the public still dubbed it as “too common.” There’s actually so much history surrounding the mom of three’s engagement ring, and it has been dubbed as a “commoners ring” even before she inherited it.

The jewelry was previously owned by Princess Diana. Unlike the other engagement rings given to royal brides, the Princess of Wales was the one who chose her ring from a catalog. As such, it was dubbed as a commoner’s ring decades ago.

And even during Middleton’s engagement, the piece of jewelry was still considered as too common. But in recent years, the value of the engagement ring has actually skyrocketed. The Duchess of Cambridge's engagement ring is also one of the most sought-after engagement rings of her generation.

Meanwhile, the Princess of Wales’ engagement ring was inherited by her youngest son, Prince Harry. But the Duke of Sussex decided to make a huge sacrifice for his older brother after Prince William told him that he wanted to marry his long-time girlfriend.

In the Amazon Prime documentary “The Diana Story,” it was revealed that Prince Harry thought it was just right for Prince William to have the ring because he got married way before he did.

And during the couple’s engagement interview in 2010, Prince William said that he decided to give Princess Diana’s engagement ring to his future wife to make sure that his mom will be with them on their special day.

Middleton’s engagement ring is set in 18k white gold and a 12-carat oval diamond centerpiece surrounded by 14 solitaire diamonds. Before their engagement, the ring was reportedly resized to fit the Duchess of Cambridge.