Lady O was actually one of the 1st acknowledged black billionairess. Isabel Dos Santos wealth has gone way over the magic number. Some estimate her fortune between $1.3 to $1.6 billion. Much of Isabel’s wealth is derived from her holdings in publicly traded European firms. Folorunsho Alakija from Nigeria is now planet Earth’s richest black woman. Conservative estimates put her net worth anywhere between $3.2 to $3.6 billion. Alakija's wealth is from the Nigeria’s booming oil business.