Keltham's diamond-making takes longer.  He does not have kingdoms and empires offering to be his purchase-agents.

Keltham tells Carissa nothing of that diamond-making, before or after.

He goes to the City of Brass alone, and in secret, and augments only himself.  He doesn't augment Strength or Dexterity, except with a belt he can remove, because it might be too visible.  He doesn't augment Splendour.

Keltham's diamond-making takes longer.  He does not have kingdoms and empires offering to be his purchase-agents.

Keltham tells Carissa nothing of that diamond-making, before or after.

He goes to the City of Brass alone, and in secret, and augments only himself.  He doesn't augment Strength or Dexterity, except with a belt he can remove, because the improvement might be too visible.  He doesn't augment Splendour.