GENEVA- Sotheby’s said Monday it would auction a pair of “phenomenally rare” blue and pink diamond earrings next month that together may fetch up to $68 million.

 “The ‘Apollo and Artemis Diamonds’ will be the stars of our May sale in Geneva - by far the most important pair of earrings ever offered at auction,” David Bennett, worldwide chairman of Sotheby’s international jewellery division, said in a statement.

The earrings comprise two large pear-shaped gems of different hues. They will go on the block separately on May 16, the auction house said, adding that the seller wished to remain anonymous. The 14.54-carat Apollo Blue, which is described by Sotheby’s as “the largest Internally Flawless Fancy Vivid Blue diamond ever to be offered at auction”, is estimated to fetch between $38 million and $50 million.

The 16-carat Artemis Pink, with its “Fancy Intense Pink” hue, meanwhile, is expected to rake in $12.5-18 million.