What's the difference? Is a Chinese, say 12K a natural stone, just from China?

Coticule is just a natural stone, right?

To my understanding a coticule can be used for well, just about anything? I'm still learning here... But seems like with slurry you can do a lot of things you'd need harsher grits for and then with water you can do fine finishing. Is this right? Okay, if it is right, is the same so for a Chinese stone?

Why one over the other?

Then we get into the Belgium or Belgian blues or whatever they are...is that another coticule just from that area? I know all are likely based on preference and none better than the other, I suppose.

Sorry, lots of questions. Perhaps this should be in the newbie section....