These companies look at the many names within the books of heraldry, pick one out and tell you that this is your coat-of-arms. If you are entitled to a coat-of-arms, you will know. It is not something that you can just do because of ancestry. It is assigned to you by the College of Heraldry. If your ancestor was John, Earl of Pembroke, you do not bear his coat of arms unless it has been passed down to you. You cannot assume a coat-of-arms on your own. Coats of arms were also issued to Titles (i.e, Count of Troye) and passed down to the eldest son. They were issued to Cities, Counties, Regions, and Countries. Today, most coats of arms either are assigned to members of royal families or are issued to individuals who have made a significant contribution to society.