London , England ( CNN ) -- They are the jewels of a royal love affair , one that led Britain 's King Edward VIII to abdicate the throne more than 70 years ago so he could marry the woman he loved . Now , the diamonds , gold , and precious gemstones that expressed the love between Edward and American Wallis Simpson are going up for auction . The 20 items being offered at Sotheby 's in London on Tuesday include 11 pieces by Cartier , some of which are estimated at more than £1 million ( $ 1.5 million ) each . `` The offering comprises not only incomparable examples of the genius of Cartier in collaboration with the Windsors , but also pieces whose inscriptions tell the story of perhaps the greatest love story of the 20th century , the romance that led Edward VIII to abdicate the throne of Great Britain , '' said David Bennett , the chairman of Sotheby 's Jewelry in Europe and the Middle East . The couple commissioned jewels from the great European jewelry houses during their courtship in the 1930s and after they were married , Sotheby 's said . Cartier was one of their favored jewelers , and the company 's high jewelry director Jeanne Toussaint created some of her best work just for the couple , who came to be known as the Duke and Duchess of Windsor . One of the pieces she created was an onyx and diamond bracelet in the form of an elongated panther . Designed in 1952 , the bracelet was among the finest of Toussaint 's `` great cats '' jewels and is in the sale at an estimated £1-1.5 million ( $ 1.5-2.3 million ) . Also up for sale is a diamond flamingo brooch with feathers of rubies , sapphires and emeralds , and a beak of citrine . The brooch , also estimated between £1 and 1.5 million , was the showpiece of an earlier sale of the couple 's jewels , held in Geneva in 1987 . All the items up for auction Tuesday belonged to a single owner , but Sotheby 's did not disclose that person 's identity . Edward had been on the throne for just 11 months when he decided to give up the crown in December 1936 to marry Simpson , an American divorcee . He chose to abdicate because , as supreme governor of the Church of England , he was not permitted to marry a divorced woman . The abdication speech he gave Dec. 11 , 1936 , revealed his love for the woman who would later become his wife . `` I have found it impossible to carry the heavy burden of responsibility and to discharge my duties as king , as I would wish to do , without the help and support of the woman I love , '' Edward said . The auction includes a favorite bracelet of Simpson 's , made of diamonds and supporting nine gem-set Latin crosses -- each with an intimate inscription on the back , Sotheby 's said . The crosses represent special moments in her life , including her marriage and the assassination attempt against the king . A heart-shaped brooch of rubies and diamonds was commissioned for the couple 's 20th wedding anniversary and features the initials W.E . -- for Wallis and Edward -- in emeralds on the front . Cartier also created a six-piece diamond-encrusted dress suite comprising a pair of cufflinks , three dress buttons and a stud , given by Simpson to Edward in 1935 to wear for the Royal Silver Jubilee celebrations and his birthday . Each cufflink features an E on one end and a W on the other . One of the buttons is inscribed on the back with the phrase `` Hold Tight , '' a favorite phrase of the couple in their correspondence before marriage . Another gift Simpson gave to her husband traces the routes of European trips they had taken together on an 18-carat gold and gem-set cigarette case . Each city is marked with a gem or diamond and is connected to the next by enamel lines . The inscription on the back reveals it was a Christmas present in 1935 . Other items in the sale include a purse made by Van Cleef and Arpels of gold mesh , rubies , turquoise and diamonds , and a series of silver items and medals once owned by Edward .
The pieces belonged to Britain 's King Edward VIII and Wallis Simpson . Edward abdicated the throne in 1936 in order to marry Simpson . The jewels are of gold , diamonds , and gemstones . Some of the items are estimated at more than $ 1.5 million .