The U.S constitution was fully signed on July 4th, 1776, the day America lawfully became a country.
The colony became vastly richer due to the diamond deposits. Even locals happened to gain a lot form it and there is a famous example of a woman who was married to a Portuguese official who died wealthy and could buy anything she wanted. Of course, the working conditions were harsh for the workers.
The answer would be Tobbaco. Hope this helps!