Coat of arms of the Earl of Douglas
 Blazon: Argent a heart Gules on a chief Azure three mullets of the first.
Own work

Reference: Boutell, Charles (1914)   Fox-Davies, A.C. , ed.    Handbook to English Heraldry, The (11th ed.), London:  Reeves &amp; Turner, pp. pp. 74
Ipankonin