Photos of Carole at Wimbledon Tennis Championship back in 2017 and 2019 gave a close-up look at her stunning rock, which features a square blue stone in the centre surrounded by diamonds.
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Although it doesn't have the same coloured stone in the middle, Pippa's ring from James Matthews is also an art deco design with a central stone set in a halo of smaller diamonds.
Diamond expert David Allen of 77 Diamonds told HELLO!: "Pippa's ring is inspired by the art deco style of the 1920s and 30s. Featuring what looks to be a four carat asscher cut diamond, it is surrounded by an octagonal surround of round brilliant diamonds to give it that feel of yesteryear. Asscher cuts are uniquely clear and require a high clarity, so if this were of top quality, this would fetch in excess of £200,000."
The Duchess of Cambridge's mother has been spotted wearing a blue gem and diamond ring
Carole has been pictured wearing her beautiful jewel on her ring finger on numerous occasions over the past few years, but it may not actually be the original one Michael gave her when he popped the question.
When the couple visited Kate Middleton and Prince William at the Lindo Wing at St Mary's Hospital shortly after Prince George was born in 2013, pictures show Carole wearing her gold wedding band next to a solitaire diamond.
Pippa Middleton's engagement ring from James Matthews
Perhaps her switch to a coloured stone was inspired by Kate's beautiful sapphire ring, which originally belonged to Princess Diana.
Carole met flight dispatcher Michael while she was working as a flight attendant for British Airways and the pair married on 21 June 1980 in Buckinghamshire.
The couple welcomed their first child Catherine in 1982, followed by Pippa in 1983 and youngest child and only son, James, in 1987.
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