The fall auction season is heating up, and Christie’s has announced that its Magnificent Jewels sale in New York will feature three exceptional colored diamonds: a rectangular-cut 8.77-carat intense-pink diamond, a cushion-cut 3.81-carat vivid-blue diamond, and a square-cut 5.13-carat vivid-yellow diamond. Additionally, the sale—on October 15th—will offer three top-quality D-color diamonds, weighing 25.30 carats, 18.28 carats, and 9.52 carats. These six notable stones are estimated to fetch between $850,000 an…