RAPAPORT... Sotheby's will offer two rare jewels with royal connectionsat its auction in Geneva next month. An Art Deco necklace will feature in the Magnificent Jewelsand Noble Jewels sale May 14. The Van Cleef & Arpels piece includesdiamonds, as well as 11 cabochon Colombian emeralds with a total weight of more than 75carats. It was created in the 1930s for H?(C)l??ne Beaumont, an American socialiteand close friend of Wallis Simpson, the duchess of Windsor. The piece has apresale estimate of $3 million to $4 million. "This is Art Deco at its absolute finest, a connoisseur'sjewel," David Bennett, worldwide jewelry chairman for Sotheby's, said Monday. "Rareand exceptional pieces like these are the reason people collect jewelry. Thefirst time I laid eyes on this emerald and diamond necklace was exactly 25years ago, when we sold the H?(C)l??ne Beaumont collection in Geneva. I said at thetime that it was the most important row of cabochon emeralds I had seen duringmy then 20-year career. Today, 25 years on, that statement still holds true." A diamond tiara, made by Faberg?(C) in 1903 for Duchess Cecilievon Mecklenburg Schwerin, the last crown princess of Prussia, will also gounder the hammer. The headpiece, which was a present from her Russian relativesupon her marriage to Crown Prince Wilhelm, is valued at $200,000 to $300,000. Other notable pieces include a brilliant-cut, 36.57-carat, D-color,type IIa diamond, estimated at $4.8 million to $5.8 million, and anemerald-cut, 18.86-carat, D-color, type IIa ring by Harry Winston, expected tofetch $800,000 to $1.2 million. Image: The Art Deco necklace (left) and the Faberg?(C) tiara. (Sotheby's)