Certificate of authenticity: what it must contain
A valid certificate of authenticity identifies the work precisely, stating author, title, year, medium, dimensions and edition numbering where applicable, and carries the signature of whoever issues it, whether the artist, their legal representative or a recognised body.
gelisted editorial team · Updated 15 August 2026
The short version
- It must identify medium, dimensions, year and numbering.
- The photograph included prevents substitution.
- Without a certificate, resale value falls appreciably.
- A certificate issued by the seller alone carries little weight.
The document does not make a work authentic. It makes it provable, and that difference shows on the day it has to be sold or insured.
What it must include
Full name of the artist. Title of the work. Year of creation. Medium and support stated precisely, not the words mixed media on their own. Dimensions in centimetres without the frame and, where relevant, with it. Edition number and total edition size for editioned work. A photograph of the work incorporated into the document. Details of the issuer with their signature. And the date of issue.
| Issuer | Weight | Note |
|---|---|---|
| The artist | very high | strongest for a living artist |
| Heirs or the artist's foundation | very high | for a deceased artist |
| Representing gallery | high | if the relationship is evidenced |
| Recognised expert | high | with a reasoned report |
| Seller with no other backing | low | not sufficient alone |
| Document without a photograph | reduced | allows substitution |
| Certificate without a signature | none |
Why the photograph matters
A certificate that describes a work without showing it can end up accompanying a different piece of similar dimensions. That is why the trade standard includes a printed image within the document itself, and on higher value works also a detail of the signature or of an identifiable area. In any dispute, that detail is the first thing an expert compares.
The rest of the file
The purchase invoice, which evidences title. The provenance, meaning the chain of previous owners, particularly relevant for older work. Exhibition catalogues in which the piece has appeared. And any conservation reports. Together those form the file of the work, and that file is what supports its value in a valuation or a sale.
Digitising the whole file and storing it separately from the work avoids losing it in a move or an incident.
If it has been lost
A duplicate can be requested from the original issuer if still active. Where the artist is living, their studio can usually reissue it with a photograph of the work. Where not, a specialist expert report is the route, costing 300 € to 1,500 € depending on complexity, and together with provenance documentation it functionally replaces the lost certificate.
The effect on price is measurable. A work with no certificate and no provenance documentation frequently loses 20 to 50 per cent of its resale value, and on editioned work the penalty can be larger because the impression number cannot be evidenced. An expert report at 300 € to 1,500 € recovers much of that difference on pieces above 3,000 €.
A file is built from 5 documents: certificate, purchase invoice, technical sheet, exhibition catalogues and any restoration report. Digitising all 5 takes 20 minutes and costs nothing, against the 300 € to 1,500 € an expert report costs when one of them is missing 15 years later.
Frequently asked
+What must the certificate contain?
Author, title, year, medium, dimensions, numbering if applicable, a photograph, the issuer with signature and the date.
+Who can issue it?
The artist, their heirs or foundation, the representing gallery or a recognised expert with a reasoned report.
+Why does the photograph matter?
Because without it the document can end up accompanying a different work of similar dimensions.
+Is a seller's own certificate enough?
Alone it carries little weight. It needs backing from an evidenced relationship with the artist or an expert.
+What if I have lost it?
Request a duplicate from the issuer, or commission an expert report costing 300 € to 1,500 €.
Sources
- 1Boletín Oficial del Estado, BOE (August 2026)
- 2Govern de les Illes Balears, Govern de les Illes Balears (August 2026)