A 75-carat pear-shaped, D-color diamond is the centerpiece of Sotheby’s New York Magnificent Jewels sale on April 17. The auction house says it is “the most important white diamond ever to appear at auction in the Americas” and “one of very few pear-shaped diamonds of D color over 50 carats to be offered in recent decades.” It is estimated to sell for $9 million to $12 million.