RAPAPORT... A storied diamond connected to the Oppenheimer family will be among the top lots at next month'sGeneva auction at Christie's, with a presale estimate of $2.5 million to $3.5million. The rectangular-cut, 25.27-carat, D-color Jonker V ring will go underthe hammer at the Magnificent Jewels sale on May 15, the auction house saidlast week. The stone was cut from a 726-carat rough South Africanfarmer Johannes Jacobus Jonker discovered in 1934. At the time, the Jonker wasthe fourth-largest gem-quality diamond ever unearthed. A subsidiary belongingto Sir Ernest Oppenheimer, the founder of Anglo American and a former De Beers chairman, bought the polished stone. In 1935, Harry Winstonpurchased the diamond and set it in a ring. Later that year, it was displayedduring the Silver Jubilee celebrations for King George V andQueen Mary. Christie's will also offer a heart-shaped, fancy-deep-blue diamondring, featuring two stones weighing 2.22 carats and 2 carats, valued at $3.5million to $4.5 million. Separately, an old cushion-cut, 118.05-carat, fancy-yellow diamondcarries an estimate of $2.5 million to $3.5 million. Other notable lots are a necklace comprising 110 natural pearlswith a presale estimate of $2.5 million to $3.5 million, and a pear-shaped,75.61-carat emerald pendant necklace expected to fetch $2 million to $3million. In addition, the Geneva sale will feature an early-19th-centuryemerald and diamond fringe necklace Henri d'Orl?(C)ans, duke of Aumale, gave tohis goddaughter, Princess H?(C)l??ne of France, for her 1895 wedding to PrinceEmanuele Filiberto of Italy. The auction will also include jewels from Cartier,Bulgari, Van Cleef & Arpels and Harry Winston. Christie's will preview the jewels in London fromApril 9 to 11, and in Geneva from May 10 to 15. Image: The 25.27-carat Jonker V diamond. (Christie's)