Very few of what can be described as All-Clad pans are straight SS–most are either clad of some variety or aluminum. The copper band you saw is an inner clad layer that is the CopperCore line’s distinguishing feature . The band is “bent backward” onto the pan exterior; it’s a deceptive indicator of how thin that copper layer really is. Copperbond is a 5-ply construction, which usually also means there isn’t much copper.
Look at your gratins’ edges with a magnifying glass. Do you see any layers, or does the edge look the same? Unless the walls are thicker than a penny, they’re probably just SS.
