Set in 1904, August Wilson’s “Gem of the Ocean” takes place in the home of Aunt Ester, who is a 285-year-old spiritual healer. When Citizen Barlow comes to her Pittsburgh’s Hill District home seeking asylum, she sends him a spiritual journey to find a city in the middle of the Atlantic Ocean. “Gem of the Ocean” is the ninth work in Wilson’s ten-play cycle that has recorded the American Black experience and helped to define generations. It carries the audience through the continuing story and struggle through the abolition, civil rights and now the Black Lives Matter movements.