Few things in life may work with professional assessments, celebrity endorsements or hallmark certifications. However, Authenticity and Trust with people are first hand values. As a professional, it is not enough to rest on laurels after making initial investments in building a brand. One has to continue living up to ones brand values (whatever they be) and give the same experience successively, each time & to everybody who relies on it. That is how 'Authenticity' is experienced and a trusting brand is built. Certifications & endorsements may encourage initial breakthrough. But it is only subsequent experiences that will put the 'Authenticity' stamp on your brand.