I usually use lightly roasted beans from either Mr. Espresso or Peet's Coffee. Their coffee bean blends are wonderful to finish roasting in my skillet.

When I first started roasting espresso coffee beans, I used raw Ethiopian coffee beans. these are greenish grey, small and hard beans that gently swell and change color like autumn leaves, from a light yellow to muddled orange, to chestnut and then coffee brown. just before the turn orange brown an outer covering or husk pops away from the skin like the golden outer layer on a corn seed before it explodes into popcorn. Stirring vigorously and gently blowing into the pan when this occurs removes the shells from your beans.