Here is how you conclude that the Company who coated your watch did work for Panerai. You call the company and start with "have you done work on an oem basis for watch companies?". Then if they say yes, you follow up with the question "what Companies have you done work for in the past?" When they answer Panerai as the second in a list of three companies I concluded they are the real deal. I am not the friend who recommended the company to Ziggy but am a different friend who called the Company and asked. But as a number of people have said - it doesn't matter who did it as long as it looks good. And your stuff looks fabulous as well.
And finally, on the question of comparing a coating with gen that is still very difficult because any gen has had skin oil and the elements degrading the finish for years.