RAPAPORT... Sotheby's will offer a D-flawless diamond over 100 carats in Hong Kong next month, taking the unusual step of selling the stone without setting a reserve price.The oval-shaped, 102.39-carat, type IIa stone is one of only eight white diamonds of that quality over 100 carats ever to appear at auction, Sotheby's said Thursday. Global manufacturer Diacore cut and polished the diamond over the course of a year from a 271-carat rough that De Beers recovered at its Victor mine in Canada.Sotheby'swill feature the diamond in a stand-alone, single-lot live auction on October 5, with online bidding beginning September 15. The company will preview the stone in Beijing, Shanghai, New York, Taipei and Hong Kong before the auction.The auction house will offer the diamond without reserve, meaning it does not have a floor price it needs to meet. Instead, the participant who places the highest bid will take home the diamond, irrespective of what Sotheby's believes the selling price should be. This is the first time in auction history an item of its importance and value has been offered this way, Sotheby's claimed. "Demand has shown tremendous resilience during the first part of the year, and we feel it is now time to let the market speak," said Patti Wong, Sotheby's chairman of Asia. "Diamonds of this caliber attract interest well beyond the traditional pool of collectors. This innovative sale seems to us the best way to introduce this exceptional diamond to the world in the current circumstances."Image: The 102.39-carat diamond. (Sotheby's)