The Duchess of Cambridge's iconic engagement ring has increased ten-fold in value since it was originally bought for Princess Diana - up from £28,000 to £300,000, according to new research

Kate, the Duchess of Cambridge's engagement ring - the most famous in the world - has increased by more than ten-fold in value, according to new research.

The beautiful blue sapphire, originally the engagement ring of the late Princess Diana, was worth £28,000 when it was bought in 1981 but is now valued at £300,000.

The stunning sparkler sits at the head of the top 20 most famous rings in the world in a list which values each ring and shows how much it has appreciated since purchase.

Kate’s ring, consisting of 14 solitaire diamonds surrounding a 12-carat oval Ceylon blue sapphire and set in white gold, has shot up in value far quicker than the other rings on the list - and is worth three times as much as the Queen's engagement ring.

The Queen's modest engagement ring, presented by Prince Phillip in 1947, has increased in value from £10,000 to £100,000 today and comes second on the list.

The Queen's engagement ring

A three-carat diamond solitaire is flanked on each side by five smaller diamonds, all set in platinum. The diamonds were taken from a tiara owned by Prince Phillip’s mother, adding a sweet heritage touch.

The Duchess of Cornwall's band - a beautiful 1930s Art Deco design - is the most expensive of the royals' betrothal rings in the list, up from £100,000 at the time of her wedding to Prince Charles in 2004 to £250,000 now.

The list was compiled by jeweller to the stars Vashi Dominguez - founder of Vashi.com.

Vashi says both the the design and the story of the Duchess’s ring has contributed to its rapid rise in value.

"The Duchess of Cambridge’s ring has appreciated more quickly than any other ring in the list,” he said.

"It’s Kate’s quiet confidence to lead as a style icon that makes the ring so special.

"Symbolically, blue can convey a sense of trust, loyalty and understanding, which is perfectly in tune with the giving of an engagement ring.

"Blue is also a colour associated with the royals, of course, so I believe it’s fitting that Kate is wearing a ring to reflect her addition into the family.”

Third on the list is Michelle Obama's engagement ring, presented to her by then-lawyer Barack in 1991. It was a worth a modest £7,500 then and its current cost is estimated at £20,000.

Its value is tiny compared to Beyoncé's engagement ring, which was worth £2,650,000 when rapper Jay-Z proposed in 2007.
The statement piece, an 18-carat diamond set in platinum, is now worth £5,800,000 but only comes 11th on the list.

Beyonce

Kim Kardashian's 15-carat bling from rapper Kanye West is the second most expensive on the list, priced at £5,150,000, and is ranked fifth.

Kim Kardashian

While they are global icons now, David and Victoria Beckham were relative novices in their careers when they became engaged. Their bride and grooms' rings cost a relatively modest £100,000 each back in 1998, but have shot up in worth to £230,000 each by 2014.

The Beckhams on their engagement

Victoria's three-carat pride and joy is marquise cut - an unusual, elegant diamond shape - while David's matching band is set with 96 exquisite diamonds; together, they come in sixth on the list.

“Even in 1998, Victoria’s ring was unusual and perhaps ahead of its time," said Vashi. "It was a sign that she would turn to fashion and become greatly successful in the industry."

Prime Minister’s wife Samantha Cameron's engagement ring is estimated to have been worth £25,000 when David slipped it on her finger ahead of their 1994 wedding. It is now worth £45,000 and comes seventh on the list.

“Samantha Cameron rarely shows off her engagement ring, so it's a treat when we see pictures of it,” said Vashi.

“Samantha appears to save the ring for special occasions rather than wear it every day.”

Angelina Jolie's 2012 engagement ring, designed by her fiance Brad Pitt, features diamonds of the highest quality cut to a size and shape to suit the screen beauty's slender hand. It originally cost £600,000, is now worth £950,000 and comes 12th on the list.

Of course, says Vashi, you can’t really put a price on a piece of jewellery that carries such emotional weight.

“All the rings are gorgeous and, despite many of them being extremely expensive, they all represent something deeply personal,” he explained.

“It's essentially about the bride-to-be's emotional connection, hence why the rings become precious heirlooms, passed down through generations - a tradition so beautifully upheld by the royal family.”