Say you have a vintage Fender Stratocaster but you're not sure fully of its origins. You can put a request in to manufacturer, Fender, and they will review the details and give you a Certificate of Authenticity that then is associated with that guitar. User pays a small fee, exactly the same as the "Blue tick" on social media sites and can add a Blue tick to that guitar as well. Vintage and high end guitars often come with a certificate of authenticity to be an aid of sale and to recognise the quality of the work.