Largest orange diamond expected to fetch $20 million at Christie’s auction

A pear-shaped, vivid orange diamond to lead Christie’s Geneva Magnificent jewels auction next month, could fetch as much as $20 million, or $1.3 million per carat, experts predict.

The auction house said in a press release it would offer the 14.82-carat rock, the largest known orange diamond in the world, on Nov. 12, just a day earlier than Sotheby’s scheduled auction of its “Pink Star,” valued at more than $60 million.

According to the Gemological institute of America (GIA) strongly coloured diamonds in the orange hue range, known as known as fire diamonds, rarely exceed three or four carats once they are polished. “The Orange” is almost four times larger than that size range.

Based on GIA’s coloured diamond grading system, as the shade of strongly coloured diamonds evolves from orangey yellow or amber to orange, the occurrence becomes progressively more rare.

The last time an orange diamond of these characteristics appeared at auction, it weighed 5.54 carats. The rock known as “The Pumpkin Diamond” fetched $1.3 million at Sotheby’s in 1997, selling to Ronald Winston, a son of Harry Winston Inc.’s founder.