Green’s Dictionary of Slang

1. racially black; pertaining to black people.

1905		Minneapolis Jrnl (MN) 29 Mar. 11/3: The jasper population seems to be short on Uncle Tom and long on cash, and they begins extendin’ the fat hand to the troupe.
1944		D. Burley Orig. Hbk of Harlem Jive 60: He lamped her [...] and then mugged behind five to his Jasper boy.

2. lesbian; pertaining to the world of lesbians.

1969

‘Iceberg Slim’ Pimp 40: There were two ‘jasper’ coeds in her dorm. [Ibid.] 97: You would also be playing your girl against a half-dozen strong, jasper whores.