LONDON (AP) — A white diamond billed as the largest and purest of its type to come to market is expected to sell for well over $33 million. Sotheby's auction house says the 102.34-carat gem mined from Botswana "is the only known round brilliant-cut diamond over 100 carats perfect according to every critical criterion" — carats, color, clarity and cut. Sotheby's diamond department head Patti Wong called it "over 100 carats of flawless perfection."