(IDEX Online) - A 1.02-ct fancy vivid blue diamond, described as the "property of a gentleman", is leading a Christie's online sale.The unmounted oval modified brilliant-cut gem carries an estimate of $405,000 to $675,000. It is certified by GIA as SI2 clarity.Among the other highlights of Jewels Online: The London Edit is a signed Cartier 32.10-ct round brilliant-cut diamond ring ($270,000 to $405,000) certified as S to T color, VS1 clarity.And a Ritz fancy intense yellow cut-cornered rectangular modified brilliant-cut 12.56-ct diamond of carats, VS2 clarity ($175,000 to $215,000).