"Diamond" was commissioned in a traditional ceremony on 6 May 2011 in her home port of Portsmouth. The ceremony was attended by the ship's sponsor and the Commander-in-Chief Fleet Admiral Sir Trevor Soar. "Diamond" continued undergoing sea trials until she entered operational service in July 2011 after the completion of her trials. The ship conducted operational training before commencing her first overseas deployment. "Diamond" is commenced her deployment in the summer of 2012, starting with celebrations to mark the Diamond Jubilee of Her Majesty Queen Elizabeth II.