These are the grandest pieces of jewellery in living memory, and they transform the wearer’s appearance more than any other kind of jewel. They have had a good 200-year run since they first emerged in the neo-Classical period (think of David’s picture of the coronation of Josephine by Napoleon), but now hardly anyone wears them besides royalty, or cod royalty (Posh Spice at her wedding to footballer David Beckham), or old queens (Elton John at his annual tiara party). Geoffrey Munn of Wartski has put together an astonishing 180 tiaras (twice as many as at the 2000 tiara show at the Boston Museum of Fine Arts) from the greatest sources, including The Queen Mother, for an exhibition that combines the highest workmanship, intrinsic worth, the most refined snobbery and delicious social gossip—or history, if you prefer. He has tracked down pieces through collateral lines of noble families, saved others from the breaker and found photographs and portraits of nearly every one of them in use (above, Princes Margaret about 1970 in the diamond and turquoise Triumph of Love tiara given to her by her mother). Artistically, tiaras are a challenge to the designer to produce multum in parvo: the architectural elements of neo-Classicism; wheatsheafs, flowers, dragon flies and other insects; the abstractions of Art Deco or the headdresses of Russian peasants. They are all here (until 14 July) in a minimalist setting, designed by Katherine Byrne, where they float against a pale ground in a darkened room: Fabergé, Tiffany, Lalique, Cartier, Boucheron...A dazzling show.