Prince Wiliam and Kate Middleton will marryin 2011

Prince William carried his late mother's engagement ring in his rucksack for three weeks before proposing to Kate Middleton in Kenya.

The oval blue sapphire, surrounded by a cluster of 14 small diamonds, was chosen by Diana, Princess of Wales in 1981 when she became betrothed to Prince Charles and cost £28,000.

‘It was my way of making sure my mother didn't miss out on today and the excitement,' William, 28, explained in an ITV interview with his fiancée last night.

‘As Kate's very special to me now, it was right to put the two together.

Kate isn't trying to fill my mother's shoes. She will create her own destiny.'

Unusually, the ring was not designed especially for Diana - then Lady Diana Spencer - she selected it from the Garrard jewellery catalogue.

Fortunately, Kate, 28, who will become Queen Consort when William is crowned, thinks the ring is ‘beautiful.'

‘I just hope I look after it,' she said. 'It's very, very special.'

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