Certificates of authenticity: what they prove

The uncomfortable bit first

A certificate of authenticity is a piece of paper that says an object is real. It is reproduced perfectly by a photocopier.

That is the whole problem, and no amount of foil, embossing, numbered stock or signature makes it go away. Whatever you can print, somebody selling a convincing fake can print. They are, by definition, already in the business of manufacturing something that looks like yours. A document is an easier thing to copy than a handbag.

So if you are about to spend money on certificates because you think they will stop counterfeiting, stop. They will not. There is a longer version of that argument in when your product is copied.

Then why does anyone bother

Because a certificate does three things that are worth having, none of which is proving authenticity.

It records what the object is. Six months after a commission, neither you nor the customer remembers whether that was Adria or nappa, or whether it was finished in March or April. A document written at the time settles it.

It signals care. A well-made certificate tells the buyer this is a thing you keep records about. That is a real message and it is honestly earned, as long as you actually keep the records.

It travels with the object. When the piece is resold, the paperwork goes with it and the second owner learns something they otherwise could not. This is the one that matters most and the one most certificates are worst at, because they are usually written as a sales document rather than as a record.

None of that requires the word "authentic" to appear anywhere.

What to put on one

The useful version is a description, not an assertion.

What the object is. Model, colourway, size, materials, finish. As specific as you are actually certain of.
When it was made, and by whom if that is a person's name your customers would recognise.
Its number, if it has one, and the size of the edition it belongs to. See numbering a limited edition for the ways that goes wrong.
A unique identifier for this object, printed as text and as a code that can be scanned. This is the part that makes the document worth more than the paper.
Where to check it. An address on your own domain, not a third party's.
How to reach you. Repairs, questions, a report that the item was stolen.

What to leave off

The word "authentic", and any variant of it. You are not in a position to certify it and neither is anybody else who was not present when it was made. Call the document a certificate of registration, or a record of make, and let it describe rather than declare.
A valuation. It will be wrong within a year, it will be quoted at you in a dispute, and in some jurisdictions it is a regulated statement. If a customer needs a value for insurance, they need an independent valuer.
Anything you are not sure of. An imprecise material line on a product page is a copy problem. On a certificate it is a false statement about the object being certified. Leave the field off rather than filling it with a guess.
The owner's name. Tempting, and it turns a document into a personal data problem the first time the piece is resold or the certificate is photographed for a listing. If you want to record ownership, that is a separate system with separate obligations.

The thing that has to sit behind it

Here is the useful reframe: the document is not the record. The document is a printout of the record.

That distinction decides almost everything.

If the certificate is the record, then it can only be as current as the day it was printed. An item that is later reported stolen carries a certificate saying nothing about it. An edition size that turned out to be wrong is wrong on every copy in the world, permanently.

If the certificate is a printout of a register, then it can be reprinted, the register can be looked up directly, and the paper is a convenience rather than the source of truth. A photocopy of it is then obviously worth nothing, which is the correct amount for a photocopy to be worth.

This is why a scannable identifier is the single most valuable thing on the page. It converts an unverifiable document into a pointer at something live.

Making the live version tell the truth

If the register behind the certificate can only ever say nice things, you have reinvented the problem with extra steps.

A register worth checking has to be able to render bad news. An item reported lost or stolen should say so, prominently, on the lookup and on any certificate generated afterwards. An identifier that was never issued should say that plainly rather than returning nothing and letting the reader assume a technical fault.

It should also return the object's identity rather than a verdict. A system that answers yes or no is defeated by copying one genuine code onto five hundred fakes: every one of them then passes. A system that answers "black tote, made 14 March, number 7 of 10" means the person holding a brown one has their answer immediately, and the forger would have to match a different real code to every individual fake.

That argument is the reason Provenance has no "authentic" state in it anywhere, and why its document is headed "Certificate of registration".

If you are printing them yourself

Practical notes, in the order they bite.

Print the identifier as text as well as a code. Phones fail, signal fails, cards go through washing machines.
Generate the document from your records rather than typing it. A template filled in by hand is a template that will eventually carry last customer's edition number.
Render on demand rather than storing a PDF. A stored file describes the item as it was the day it was made. A rendered one describes it as it is.
Do not laminate. It makes the document feel permanent, which is exactly the wrong message, and it makes reprinting look like forgery.
Decide the layout before the first print run, including any space you might want later. Adding a field to a design after two hundred certificates are in the world means two hundred documents that do not match.

Certificates of authenticity, and what they are actually worth