Coat of Arms of Kate Middleton (prior to her marriage to Prince William the Duke of Cambridge on the 29 April 2011); the arms are derived from those granted to her father (Michael), borne on a lozenge as an unmarried woman. This coat of arms in this form is now used only by her sister Philippa Middleton.Blazon: 
On a lozenge, "Per pale Azure and Gules a Chevron Or cotised Argent between three Acorns slipped and leaved Or"
Own work, Created from blazon provided by: The Official Royal Wedding Website
Coat_of_Arms_of_Catherine_Middleton,_Princess_William_of_Wales.svg: Sodacan
derivative work: Sodacan (talk)