“Gem of the Ocean” premieres tomorrow night at Chattanooga Theatre Centre. The play by August Wilson is part of his American Century Cycle. Chronologically, it is the first of his ten plays on the African-American experience, with each play set during a decade of the 20th Century. Sadiqua Iman is director of “Gem of the Ocean” - and the first black woman to direct a show at CTC in its 96-year history…