RAPAPORT... A flawless white diamond with a high estimate of nearly $13million will head up April's Magnificent Jewels and Jadeite auction atSotheby's in Hong Kong. The oval brilliant-cut, 88.22-carat, D-color, flawless, typeIIa stone is one of only three oval diamonds over 50 carats offered in auctionhistory, Sotheby's said Tuesday. The stone - which has a presale estimate of$11.2 million to $12.7 million - is the largest to go under the hammerin more than five years. "For those who have had the chance to see the diamond, oneadjective comes back: 'breathtaking,'" said David Bennett, worldwide chairmanof Sotheby's international jewelry division. "Barely any diamonds of thisweight are known to possess the same exceptional qualities of purity andperfection as this remarkable stone, which is so full of fire and blindingbrilliance." The diamond comes from a 242-carat rough stone recovered fromDe Beers' Jwaneng mine in Botswana, and took several months to cut and polish,Sotheby's added. Image: The 88.22-carat oval diamond. (Sotheby's)