The princes said in a statement Sunday that the statue is meant to create "a fitting and lasting tribute to our mother" and to remember her life and legacy.
In January, the brothers commissioned a statue in honour of their mother, who died in a Paris auto crash 20 years ago to be erected outside their official London home Kensington Palace.
The princes also said they've been touched by the kind words and memories shared with them about Diana this year.
"The statue, which will be erected in the grounds of Kensington Palace, will celebrate the late Princess's life and legacy", the palace said.
"It is clear the significance of her work is still felt by many in the United Kingdom and across the world, even twenty years after her death", they said.
Off-duty cop robbed of his gun in fight outside Bronx nightclub
Police say the officer was arguing with a group of men when they began beating him, then took off with his gun. He was being questioned at the 46th Precinct on Sunday and had not been arrested or charged, the police said.
The brothers are understood to be particularly keen on seeing a true likeness of their late mother, a style Rank-Broadley is famous for.
Rank-Broadley recently finished work on the Armed Forces Memorial and his effigy of Queen Elizabeth II has been on Commonwealth coins since 1998.
Then, Rank-Broadley said there was "no need to disguise the matureness of the Queen's years", adding: "There is no need to flatter her".
Diana was 36 years old when she died in August 1997.
'It is clear the significance of her work is still felt by many in the United Kingdom and across the world, even 20 years after her death.
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