The jewellery, a 90 piece taster of the over 800 items going under the hammer at Christie's in London, was once the property of the Queen's younger sister Princess Margaret.It's the first time in history that the private collection of a reigning monarch's sister has been put up for public sale and for Christie's it's the closest, they say, they've got to actually selling the crown jewels.The jewellery collection owned by the Queen's late sister, who died in February 2002, is being auctioned off by the Princess's son Lord Linley to pay the inheritance tax due on her estate.But before they go to sale some of the highlights from the "personal and very touching jewellery collection" are being exhibited over two days in the Double Cube Room at Wilton House near Salisbury.Princess Margaret's wedding day in 1960 Spanning every stage of the Princess's life, all the jewels on display have been either, inherited, given or acquired by the Princess and kept in her private collection at Kensington Palace.Amongst the most significant pieces in this unparalleled and historic sale is a diamond and pearl necklace given to the Princess by her grandmother, Queen Mary, on her 18th birthday in 1948.A year later, to mark her 19th birthday, the Princess was photographed by Cecil Beaton wearing the necklace and again she chose it for her 21st birthday portrait. Art Deco pearl and diamond necklace Also on show is a stunning diamond tiara which is expected to fetch up to £200,000. The Princess wore it on several occasions including her wedding day, in May 1960, when she married Anthony Armstrong-Jones at Westminster Abbey.A Victorian bee brooch, once owned by the Queen Mother, is among the more personal items of jewellery included in the sale. The brooch, which is expected to raise £700, is accompanied by a note in Princess Margaret's hand which says: "Almost the first bit of jewellery given to Mum…given to me 10 Feb 1945."Another piece, a sapphire and diamond bar brooch, is personally annotated by Queen Mary with the words "For darling Margaret on her confirmation day from her loving Grannie Mary R. God bless you. April 15th 1946".Princess Margaret on her 19th birthday With security expected to be stepped up by Christies ahead of the collection going on display at Wilton House... it's surprising to find out that visitors to the Cube Room will not only be able to have a look at a slice of Royal history but try it on as well.Unbelievably, during the two day exhibition, visitors will actually be able to try on some of the items on display.... So if you've ever wanted to slip a Royal tiara on to your commoner's head than Wilton House is the place to head.The Jewellery Highlights from the collection of HRH Princess Margaret will be on display at Wilton House from Monday 8th May through to Tuesday 9th May, 2006. The exhibition is open from 10:30 am to 5:30pm with last entrance at 4:30 pm. For more information click on the link in the right hand column.