The world's largest blue diamond is up for auction at Christie's on Wednesday with a whopping $25 million price tag.
"The Blue" is expected to fetch between $21 million and $25 million when it is auctioned at Christie's auction house in Geneva later on Wednesday.
The sparkling 13.22 carat gem – which is set between two pear-shaped diamonds -- is described as "the largest flawless vivid blue diamond in the world."
"It is much rarer to find a blue diamond than any size of white diamonds," Christie's told CNBC via email.
"To find coloured diamonds which are flawless, meaning with no inclusion at all, is adding to its rarity, as well as its colour intensity, which is vivid blue, the strongest in the world."
It will lead the Magnificent Jewels sale, a 250-strong set with an estimated value of $80 million, being held at the Four Seasons Hotel des Bergues.
Among the lot is "The Ocean Dream" – a 5.50 carat diamond that is "the largest, fancy vivid blue-green diamond in the world to come to auction".
It is expected to fetch up to $9.5 million and its size, natural origin, hue and saturated color make it an extremely unusual occurrence.
Auctions of precious gems often squeeze eye-wateringly high prices out of bidders.
Read More'Pink Star' diamond sells for world record $83 million
Last year Christie's sold "The Orange" – the largest fancy vivid orange diamond in the world – for $35.5 million.
This set a world record for an orange diamond and it was a world record auction price per carat for any diamond at $2.4 million.
Last year Sotheby's Geneva auction house sold the "Pink Star" diamond for a record $83 million - $23 million above the asking price.
But it was later forced to buy back the gem after the buyer defaulted.
Follow us on Twitter: @CNBCWorld