Greetings defenders of straight razor shaving....

So I was looking at a straight razor the other day and a question came to mind. When one buys a straight razor, oh say from ebay, how do you know when to set the bevel or just sharpen it on a finer grit stone? I guess what I am asking is what do you look for? If I were to look at a razor's bevel and it looked even but was not totally sharp, I would just assume that you could use a fine grit stone and sharpen it right up and it would be good. Am I way off base or kinda in the ball park? You'll have to excuse my ignorance if this seems like a silly question.

What stone would you use to just sharpen the razor? Maybe 12K??????