The world’s largest blue diamond will go under the hammer in Geneva next month, with the rare gem expected to fetch up to $25 million.

“The Blue”, a shimmering pear-shaped rock the colour of cobalt and weighing 13.22 carats was described by Christie’s as “the largest fancy vivid blue diamond in the world.”

The gem will be the centrepiece of the auction house’s “Magnificent Jewels” sale in Geneva on May 14, with an asking price of $21-25 million.

If recent auctions in Geneva are any indication though, it could fetch far more. When the world’s largest orange diamond, a 14.82-carat gem called “The Orange”, went under the hammer last November at Christie’s, it raked in $35.5 million compared to its $17-20 million price tag.

And a Sotheby’s auction the next day saw the world’s largest pink diamond, known as the Pink Star, fetch $83 million.

The auction house was, however, forced last month to take back the Pink Star after the buyer defaulted on the payment.

Christie’s said its auction next month would comprise 250 pieces at a joint estimated value of $80 million. Among other notable gemstones will be a 5.5-carat vivid blue-green diamond named “The Ocean Dream”.

Competitor Sotheby’s will meanwhile hold its Magnificent Jewels sale next door on May 13, auctioning off one of the world’s largest yellow diamond.

The Graff Vivid Yellow, the colour of a daffodil and weighing 100.09 carats, has been valued at up to $25 million.