Coat of arms of the Earls of Douglas
Blazon: Argent a heart Gules imperially crowned Or on a chief Azure three mullets of the first
SVG elements from 

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