(IDEX Online) - A diamond and platinum bandeau tiara, signed Boucheron Paris and owned for over a century by a British aristocratic family, is to be sold at Christie's London with a high estimate of $185,000.It's the most valuable of three tiaras offered at Christie's Jewels Online: The London Edit, which runs from 2 to 15.The double bandeau, featuring old- and rose-cut diamonds, comes complete with a screwdriver, allowing one band to be detached so it can be worn as a single bandeau.The Art Deco style piece has belonged to the same family since 1911, and has been worn at at State Openings of Parliament as well as receptions at Buckingham Palace.The condition report says the estimated total diamond weight is 17.00-18.00 carats (excluding rose-cut diamonds), with the largest old-cut diamonds weigh approximately 0.75 carats, approximately G-I color, SI clarity on average.Two brackets to the reverse can be unscrewed, using the supplied screwdriver, allowing for the bands to raise and lower through a hinge in the roundels on each side.Boucheron has a longstanding reputation for creating some of the most spectacular tiaras of the last century, supplying jewels to royalty and aristocracy across Europe.Two other tiaras, both from around 1900, are to be sold - diamond aigrette/tiara, circa 1900, with fittings to convert to a hatpin, brooch or pendant (high estimate $43,000) and a diamond and pearl tiara, which can also be worn as a necklace (high estimate $15,000).Pic courtesy Christie's