Throughout the first season, it was initially implied that this Glomgold is South African but pretends to be Scottish in order to outdo Scrooge McDuck.

This is confirmed in the second season episode, “The Ballad of Duke Baloney!”, where it is revealed that Glomgold was born Duke Baloney, a shoeshine boy who did Scrooge’s shoes and given a dime as payment to teach him self-reliance, only for Duke to instead feel cheated and create his “Glomgold” persona over the years to get revenge.

Glomgold was originally depicted as a diamond miner of South African descent. Some later incarnations have altered his ancestry to that of Scottish descent, to better reflect Scrooge’s own heritage. Though the character was seldom used during Barks’ tenure, Glomgold rose to prominence due in part to usage by comic artist Don Rosa, and a recurring role as a villain in the DuckTales franchise.

via fandom wiki