Arthur Charles Fox-Davies argued extensively in his book The Art of Heraldry: An Encyclopaedia of Armory that, though extremely rare, the colour white existed as an independent tincture in heraldry separate from argent. He bases this in part on the "white labels" used to difference the arms of members of the British Royal Family. However, it has been argued that these could be regarded as "white labels proper", thus rendering white not a heraldic tincture
From Wikipedia, the free encyclopedia