If you search you will find a thread with pictures of magnified nozzle seats. It clearly shows the difference between several grades of nozzle quality. The biggest difference is in the polished finish of the valve seats where the high pressure sealing and injecting take place.

You cannot see this with your naked eye or with a desk magnifying glass. You need at least a loupe, that is one of the tools I use. Anything else is speculation or a sales pitch.