Prince William. (Chris Jackson/Getty Images)

Prince William celebrated his 30th birthday Thursday with a low-key private party, according to palace officials — and $15.5 million inherited from his mother, Diana. Under revised terms of her will, William and Harry share the estate of the late princess — stocks, cash, and personal items now estimated at about $31 million — paid out to each son when they turn 30. William gets his half now; Harry has to wait until September 2014.

Read more: Prince William celebrates 30th birthday in private with Kate between Jubilee, London Olympics (AP)