The coat of arms of Jean Le Viste, the patron of the series of paintings The Lady and the Unicorn (as featured in the Harry Potter movies) is "gules on a bend azure three crescents argent". Don't believe me? Check out pictures here and here. Or do these predate the tincture rule?
I've also wondered about the coats of arms of two Cambridge colleges, Christ's and St. John's, ever since I saw them on the walls of the Boots Chemist in the city. According to this, they have the same blazon:
Quarterly; 1 and 4, Azure, three fleurs-de-lis or; 2 and 3, Gules, three lions passant gardant in pale or; all within a bordure compony argent and azure.
The quarters are one of the old royal coats, of course. On the shop wall, they two coats arms do in fact differ by the number of the "compones" on the "bordure". Perhaps the blazons are not quite accurate?