LONDON, England (CNN) -- Jewellery, art and furniture belonging to Britain's late Princess Margaret including the tiara she wore to her wedding have gone on display in London ahead of being put up for auction.

Christie's unveiled the entire collection of 800 pieces -- including the historic Poltimore tiara -- for the first time prior to the sale over two days next week.

The former possessions of the sister of Queen Elizabeth II range in value from £50 ($92) to £500,000 ($924,000) and "reflect her celebrated style and timeless elegance," Christie's say.

The auction house says that of the jewels that although not part of the Crown Jewels or the Royal Collection it is the first time that the private jewellry of the sister of a reigning British monarch has been offered for sale.

The items are being sold by the princess's children Viscount Linley and Lady Sarah Chatto. The money raised, expected to be in the region of £3 million ($5.5M), will be used to help pay off inheritance taxes on the queen's sister's estate, the UK's Press Association reported.

The Poltimore Tiara, which was originally created by Garrards in 1870 for Lady Poltimore, the wife of the second Baron Poltimore, is estimated to be worth between £200,000 and £300,000 ($369,000 to $553,000).

The princess, who died in 2002 following a stroke, wore it on several occasions, including at her wedding to Lord Snowdon, and, in its alternative form, as a diamond fringe necklace and scroll brooches prior to their marriage.

Also for auction in the first day of the sale is the cherished five row pearl and diamond Art Deco necklace which the princess wore when she was photographed by Cecil Beaton for her 19th and 21st birthdays and which is expected to be sold for up to £20,000 ($36,900).

There have been reports that Lord Snowdon was unhappy that some of the items were being auctioned, PA said.

Lord Snowdon, who was married to Margaret between 1960 and 1978, wrote to Christie's questioning whether his children had the right to sell them. However, Christie's said that there was no question of any of the pieces being withdrawn from the sale.

"This private matter has been resolved," the auction house said in a statement. "No items have been withdrawn from sale and there is no dispute about the title of the property."

Faberge

A delicate Faberge clock which was also a gift from Queen Mary looks set to fetch up to £800,000 ($1,475,000).

There is another Faberge clock once owned by the grandson of Tsar Nicholas I of Russia -- estimate £70,000 to £100,000 ($129,000 to $184,000) and a Louis XVI-style jeweled and enameled gold cigarette case, valued at up to £20,000 ($36,900).

There is also a gilt hedgehog brooch valued at just £50.

A further sale of silver, furniture and works of art from the princess's collection follows a day afterwards "offering collectors a chance to acquire interesting items with estimates starting from under £100 to to more than £30,000 ($184 to $5,300)," Christie's say.

Leading the second day of the sale is a portrait of Princess Margaret painted in 1957 by Pietro Annigoni ("Estimate on request," say the auction house).

Adds Christie's: "Additional works of historical importance include Queen Alexandra's fan, presented to her by her sister Marie Empress of Russia and given to Princess Margaret by her grandmother Queen Mary in 1932." The estimate is £400 to £600 ($70 to $1,100).

Furniture, silver, works of art, jewellery and decorative objects from the Collection of The Princess Margaret, Countess of Snowdon, are to be sold at Christie's London on June 13 and 14.

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