Green’s Dictionary of Slang

sealskin adj.

also seal
[the smoothness of the skin]

(US) usu. of a woman, black.

[US]W.R. Burnett High Sierra in Four Novels (1984) 361: I’m going to take a trip down to the islands and take a bang at some of them sealskin babes.

In compounds

sealskin brown (n.) (also seal brown)

(US) a black woman with a relatively dark skin tone; also as adj.

[US]Clara Smith ‘Clearing House Blues’ [lyrics] Since I lost all my change I lost my sealskin brown.
[US](con. 1900s–10s) Dos Passos 42nd Parallel in USA (1966) 321: He’d been all-over and had had high yallers and sealskin browns down New Orleans and Chink girls in Seattle.
[US](con. 1920s) Dos Passos Big Money in USA (1966) 1147: He whirled her round until the sealskin browns and the high-yallers cheered and clapped.
[US]Z.N. Hurston ‘Story in Harlem Sl.’ Novels and Stories (1995) 1008: Colorscale: high yaller, yaller, high brown, vaseline brown, seal brown, low brown, dark brown.
[US]‘Touré’ Portable Promised Land (ms.) 40: Wit his horn in his hand and on his arm a sealskin-brown broad.