The biggest white diamond ever auctioned will go under the hammer this week in Geneva, as part of a Christie's sale that includes two stones weighing more than 200 carats apiece.
The auctioneer expects "The Rock," a 228.31 carat pear-shaped stone nearly the size of a golf ball, will fetch up to $30 million.
A 555.55-carat black diamond thought to have originated from space is for sale.
The world's biggest blue diamond sold at auction for $57.5 million.
Sanctions against major producer Russia, as well as the resumption of VIP gatherings as pandemic restrictions ease, have boosted diamond prices.
"The Rock," which was mined in South Africa, was once worn as a Cartier necklace by its former owner.
The previous white diamond auction record was a 163.41 carat stone sold in 2017.