JimmyHAD, yesterday 11:21 AM
"One barber in particular would take his thumb and flick the point to make a ringing noise. He told me that if the razor didn't "ring" it was not as good as one that did. I'm not saying that is a fact rather just mentioning what he said."

Same basic idea as the 'singing sword' from tales of the old knights. The best sword would sing when you flicked it.

Now a razor that does not sing will cut whiskers. But you will get peak performance with an ultra thin edge, only a few molecules thick. Your barber's thumb test indicates that you have the 'fin' (can't think of a better word for it).

If the edge is not ultra thin when you first get the razor, you have to think through the geometry to get it there. But once you get there, you can maintain the edge for quite a while.

And you will know you can do it; that's worth something, eh?