Get cracking...

When a coffee roaster says he's about to "get crackingf". When coffee reaches it's first level of "done-ness", it cracks rather loudly. This is called "City roast". As it cooks further, it stops cracking and that's "City+ roast", then it becomes browner and browner, reaching "Full City roast". Then the coffee starts cracking again, but it's a soft snap rather than a crack. That's "Full City+ roast". From there things happen quickly and the coffee goes from "Vienna roast", to "French roast", to "Italian roast", to "Spanish roast", to charcoal in a very short time.