A necklace worn by Diana, Princess of Wales on her last public engagement before her death has been sold at an auction in New York.

The pearl and diamond "Swan Lake" necklace was sold to a US collector for �362,500.

A pair of matching earrings were also sold at the packed sale at auctioneers Guernsey's.

Diana wore the necklace to the royal gala performance of the ballet Swan Lake at the Royal Albert Hall in London in June 1997 - three months before she died in a car crash in Paris on 31 August.

The jewels, made by London-based Garrard's, which has since merged with royal jewellers Asprey, were sold to 48-year-old Texan memorabilia collector James McIngvale. He made his bid for the jewels by telephone.

A Guernsey's spokeswoman said millionaire Mr McIngvale was expected to put the jewels on display at his Houston furniture business.

She said: "There was tremendous interest in the necklace and the earrings and the buyer intends to display them at his showroom. He was delighted to have been successful in making their purchase."

Earlier this year Mr McIngvale bought rock legend Elvis Presley's favourite car - a 1956 Mk2 Lincoln Continental - at another New York sale.

The necklace was offered for sale by an unnamed English businessman, who had bought it for his wife after being "discreetly advised" of its availability after the princess returned it to Garrard's.

The catalogue for the auction said the jewels had been put up for sale because "the couple's life centred in the countryside without suitable occasions for wearing jewels as prominent as these".

The spokeswoman added that the couple would be making an undisclosed but "significant" donation to the Diana, Princess of Wales Memorial Fund from the proceeds of the sale.

The necklace was created by Garrard's in the spring of 1997 with Diana's "knowledge and assistance" and included five of the princess's favourite jewels - South Sea pearls.

She wore the necklace to the gala performance of Swan Lake with a sky blue beaded evening dress before returning it to the jewellers for the accompanying pearl and diamond earrings to be completed.

Her death shortly after the "suite" was finished meant the jewels were the only known piece worn by Diana that was likely to be available for auction, the auctioneers claimed.