RAPAPORT... Bonhams will offer an 18.04-carat diamond at its FineJewelry sale in New York next month, estimating the piece at $400,000 to$600,000. The emerald-cut, G-color, VS2-clarity diamond flanked bytrillion-cut diamonds will head up the auction on December 3 at the company'sMadison Avenue location, Bonhams said Thursday. "This is a beautiful example of a large, white diamondexhibiting sensational fire and cut," said Caroline Morrissey, senior jewelryspecialist at Bonhams New York. "It comes from a private collection, and [this]will be the first time it has appeared at auction." The sale will also feature a ring containing arectangular-shaped, emerald-cut, 33.03-carat Sri Lankan (or Ceylon) sapphireflanked by a combined 1.25 carats of baguette-cut diamonds. Bonhams expects itto fetch $250,000 to $350,000. Image: An 18.04-carat diamond ring that Bonhams will auction in New York. (Bonhams)