(IDEX Online) - A bracelet featuring a 43.10-carat royal blue Kashmir sapphire and a total of 67.90 carats of diamonds goes under the hammer at Christie's tomorrow with a high estimate of $7m.It's the lead item in the Magnificent Jewels sale in New York.The cushion-cut sapphire (pictured) has no indications of heating, according to the SSEF grading lab, and is aged at 21 million years.It is set in platinum with pear brilliant-cut diamonds of 8.94, 8.82, 5.35, 5.25, 3.01, 2.03, 2.02 and 1.92 carats, and 60 more, of 0.76 to 0.25 carat.All the larger diamonds have been graded as D color, IF clarity by GIA. The 60 smaller stones are D to E color, IF to VS1 clarity.The sapphire and larger diamonds can be detached and worn as a brooch.Christie's describe it as "a truly exceptional piece", with an estimate of $5m to $7m in a Covid-friendly sale, with absentee bids taken in advance and live bidding by phone and online.