In the art world certificates of authenticity are used to place a value on the art. If it has a certificate therefore it is genuine and therefore more valuable. They also provide an added benefit in protecting copyrights.
I the past I have never provided a certificate of authenticity. In the past I was selling originals to friends or at the various art shows. I even traded them for luxury items, like for rent, many years ago. Pretty much they all knew who I was, so there was never any doubt about who made it. Over the years I've wondered what's happened to my creations out there in the world.
What about copyrighting the artwork? I've not put much thought into copyright other than I put the notice up where needed. At this point in my art career I'm not to worried about someone "copying" me. If they did I'd be honored that they went to the trouble to do it. Copyrights only work if the person on the copying end respect and follow copyright law. Sides I can only hope if someone ever does copy me, that they make more money than me from it. Then I can copy their marketing and apply it to my own work. But I really don't see that day coming anytime soon.
About 6 months ago I started putting labels on the back with a brief description about the creative process. I also note if it's part of a series or one-off kind of thing. I also leave my phone and email there too. I ask the new owners to send me updates on how they are fairing in the world.
So far no one notices the label until I point it out. So does that give it a certificate of authenticity? I'm still not sure. No one's written back yet, but then again I've only started to do that. So did me attaching this label add value to the art? I personally don't think so. If you are collector of art and are looking to resell it I'd say sure. But let's face it. Is a reseller going to share the profits they make? The only reason I added these labels on so they could phone home if needed.
So if you absolutely need some certificate written to confirm that I am whom I am and that I made this, then by all means let me know. Just remember you might have to wait until I'm dead before its authenticity matures.
I look forward to your letters.