courtesy sothebys
A rare Fancy Vivid Blue diamond ring valued at $25 million will go up for auction on November 16. The diamond is known as the Sky Blue diamond.
Courtesy de Grisogono
In September, Swiss jewelery and watch company de Grisogono brought the world's most expensive rough diamond to auction -- valued at $63 million.
courtesy christies
The "Aurora Green" is the largest Fancy Vivid green diamond ever sold at auction. The stone went under the hammer on May 31, 2016 at Christie's auction house in Hong Kong, selling for $16,818,983.
Christies Images Ltd 2016
The world's largest blue diamond, an extremely rare gem known as "The Oppenheimer Blue", sold for $57.5 million at Christie's Geneva May 18, 2016, making it the most expensive diamond ever sold at auction.
Christies Images Ltd 2016
The 14.62 carat Fancy Vivid stone is mounted on a platinum ring and flanked on either side by a trapeze-shaped diamond.
courtesy sotheby's
'The Unique Pink' is the largest Fancy Vivid pink pear-shaped diamond to ever be offered at auction.
courtesy sotheby's
The diamond was sold for $31.6 million by Sotheby's, at an auction in Geneva. The price makes it the most expensive Fancy Vivid pink diamond to sell at auction.
Bloomberg/Bloomberg/Bloomberg via Getty Images
Cubic zirconia replicas of the original and a modern cut of the Kohinoor diamond, one of the oldest and most famous diamonds in the world.
CNN
The De Beers Millennium Jewel 4 has broken auction records in Asia.
courtesy sotheby's
The stone sold for $31.8 million, which makes it the most expensive piece of jewelry sold at an auction in Asia.
Sotheby's
Sotheby's auctioned this 9.54 carat ring it says belonged to child star Shirley Temple on April 19, 2016. Though it was expected to fetch between $25 million and $35 million, it failed to sell.
FABRICE COFFRINI/Getty Images
This 12.03-carat blue diamond fetched $48.4 million at auction on November 11, 2015. It was previously the world's most expensive price-per-carat diamond sold.
FABRICE COFFRINI/Getty Images
The fancy, vivid blue diamond was discovered in South Africa in January last year.
EMMANUEL DUNAND/AFP/Getty Images
In recent years, other high-value diamonds have hit the auction block. The 59.60-carat oval cut pink diamond known as "The Pink Star," went for $80 million at a 2013 Sotheby's auction. However, after the buyer defaulted on payment, it was returned to Sotheby's.
Peter Macdiarmid/Getty Images Europe/Getty Images
This 118.28 oval white diamond became the largest sold at auction when it went for $30.6 million at a Sotheby's auction in 2013.
Courtesy Sotheby's
In April 2015, a 100-carat, emerald cut, D color, internally flawless diamond -- the largest of its clarity and cut to ever be shown at auction -- sold for $22 million.
FABRICE COFFRINI/AFP/Getty Images
The 76.02-carat 400-year-old Archduke Joseph diamond set a new record for price per carat for a colorless diamond in 2012, when it sold for $21.5 million at a Christie's auction.
Courtesy Chow Tai Fook
In 2010, Hong Kong's largest jewelry retailer, Chow Tai Fook, bought one of the world's largest rough diamonds for $35.3 million.
Courtesy Chow Tai Fook
Jeweler Wallace Chan and a team of craftsman worked 47,000 hours to transform the stone it into this piece, which Chai Tai Fook estimates could be worth $200 million.
CNN  — 

A rare blue diamond could fetch $25 million at auction this week.

The 8.01 carat, square cut ‘Sky Blue Diamond’, set to go under the hammer at the Sotheby’s Magnificent Jewels and Noble Jewels sale on November 16 in Geneva, Switzerland, is one of the largest blue diamonds of its type ever to be sold at auction.

Although just one of the 345 rare items being offered by Sotheby’s, the diamond stands out as a catalog highlight.

Other items of note include a historic 18th century Russian diamond brooch valued at between $3 and $5 million and a 17.07 carat pink diamond which is expected to sell for upwards of $12.2 million.

A rare gem

courtesy sothebys

The Sky Blue Diamond, which is set in a Cartier ring, has been graded as Fancy Vivid Blue of a natural color with a VVS1 – or almost perfect – clarity classification by the Gemological Institute of America (GIA).

A Fancy Vivid blue is particularly special, it describes the highest possible color rating for this diamond,” diamond expert Tobias Kormind told CNN previously.

Blue diamond records

What makes the Sky Blue Diamond particularly interesting is not only its grading, but also its color.

“Blue is the color of trust, honesty, loyalty, reliability and responsibility. This idealistic color inspires higher ideals, and evokes peace and tranquility,” Sotheby’s says in its catalog notes on the stone.

Sothebys

Blue diamonds are especially rare, and although prices for other colored gems have risen of late, demand for these blue-colored sparklers has spiked in recent years.

In November 2015, a 12.03 carat blue diamond – bought by Hong Kong businessman Joseph Lau for $48.4 million – made headlines at the time for being the world’s most expensive diamond ever sold.

Lau, who named the gem “The Blue Moon of Josephine” after his 7-year-old daughter, also purchased a $28.5 million, 16.08 carat pink diamond the previous day.

Christies Images Ltd. 2016

In May 2016, the world’s largest blue diamond – a 14.62 carat gem called ‘The Oppenheimer Blue’ – stole the title of the world’s most expensive blue diamond ever, selling for a cool $57.5 million.

It still retains that title today.

The Sky Blue Diamond is being offered for sale by Sotheby’s on November 16, 2016 and has a pre-sale estimate of $15 million to $25 million.