Isaac/Itzhak: The English nickname is IKE. Gershon Legman said it’s from the taunt” Ikey, Kikey!”

Nice to see “polished up”, that’s the orthographically correct equivalent of “phonetically” written All POSHED UP, whence POSH… Poshed digs > posh digs…>

Of uncertain relevance:
June 1902 The Era 9.6. “Aaron Levi’s Repentance,” David Felsberg, page 670:
“In the midst of the inarticulate roar, single voices were occasionally heard: ‘Shpunsh kike, shpunsh kike, ight cent a pount!’….Here was a young woman dexterously fishing for live carp in a huge tank; next to her stood a boy yelling ‘Shpunsh kike,’ and weighing a pound of that delicacy with fish scales and moisture clinging to it….”

Jan. 1909 The American Magazine 67.3. “Groping Children,” James Oppenheim, page 298:
“‘Why shouldn’t I be ashamed? look at them–kikes, Yiddish; hear their broken English; see how they live….’ ‘You!’ he added. ‘Now let me tell you something! They are Russian jews–true! But who are you?….You, too, are a Russian Jew…_polished up_!’”