How do I make a coat of arms official?

You apply to your country's heraldic authority, which grants arms by a document called letters patent. For England, Wales and Northern Ireland that is the College of Arms. Scotland has the Court of the Lord Lyon and Canada has the Canadian Heraldic Authority. The United States has none.

Each authority decides who qualifies. The College of Arms grants arms to people it judges eminent, which in practice can mean honours, a university degree, a professional qualification or public service. Americans who descend from a British subject can apply for honorary arms. The Chief Herald of Ireland has paused new applications for now.

The heralds settle the final design with you, so your sketch is only a starting point. Expect many months and real fees, listed in how much does a coat of arms cost. Plenty of people sketch ideas in the coat of arms maker first.