I would say the best way would be to make an appointment with at least one professional that has the qualifications to diagnose it. I few parents I know are kind of "autism-happy" with saying their child has it when it might not be the case. I also know of one child that I think was misdiagnosed by a professional, so multiple opinions is a good choice.
I dated an INTJ with it. He didn't define himself by it, and he was never formally diagnosed, but he knew he did. Having a relationship/friendship with someone who has Aspergers is not easy. There are many characteristics that I'm sure you can find online or ask a professional.
The simplest thing I guess I noticed is that there is a serious emotional cut off, unable to relate, communicate feelings directly or express personal emotions. There was no awkward laughing off of things or trying to console others in distress, just a complete cut off like I've never seen in anyone else. It's not that he didn't want to communicate his emotions, he just could not.