On the older Calphalon (before the new Calphalon One - I haven't looked at it in person so I don't know about it) if the inside of the pan is the same matt gray on the instide as the outside - it's not non-stick. If it is non-stick, the surface will look a little slicker, be a little different color than the outside, and have a little silvery sheen to it. That's the way mine are.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain