I think we give a lot of authority to professionals, but the literature on narcissism often points out that even very skilled therapists are often fooled by narcissists. So, imho, it doesn't really matter if someone has been formally or "officially" diagnosed. Except in the rare case when a narcissistic person is seeking therapy to change those behaviors (which most aren't motivated enough to do). Some are, I'm sure.
Anyway, I haven't learned all the sub-types, don't fully understand the "inverted narcissist" model. But the basic building blocks in the DSM-IV are good enough for me. And they're not hard to spot.
Who but a child or spouse who lives or has lived FT with a narcissistic person and who has achieved enough emotional distance, even temporarily, is better equipped to have the penny drop in that moment when they say to themselves: Oh my god! It is NARCISSISM that I'm dealing with!
I think there is a moment of truth in that recognition that it would be very hard to get wrong. For me, what has happened in the years since I discovered the literature about Nism is that I have only modified my perception of the degree of my mother's narcissism, or narcissistic tendencies, or however one might put it. But the FACT of it, the reality of the behaviors (and their emotional impact on me, which continues to reveal itself over time) is unchanged. I mean, for me, it is a piece of truth.
The farther along time marches me from the first shock of recognition, the more I (thankfully) lose interest in narcissism itself, and feel more curiosity and engagement with other issues about being a human being and having a life. The most interesting (and destructive) thing about narcissism is its secretive, chameleonlike nature...how a smooth genial "personality" can allow the N (or Nish person) to function quite smoothly in the social world, year after decade, even throughout a long life. But behind the curtain, some person, often a child, is paralysed in the wings, knowing only that something is wrong.
Finding out that this something has a name has been one of the biggest revelations in my life.
Hops