I suspect a relative might have narcissistic personality disorder. what are the most common symptoms/traits and how is it usually diagnosed?

Some obvious signs..: Narcissistic personality disorder: grandiose sense of self-importance, having arrogant behavior or attitude, a need for excessive admiration, having interpersonally exploitive behavior, with a lack of empathy, is envious of others or believes that others are envious of him; has a preoccupation with fantasies of unlimited success, power, brilliance, beauty, etc...