When purchasing a fine painting I know an increasing number of clients are very keen to see their purchases accompanied by a Certificate of Authenticity. In the UK this means that whether they are buying from a gallery in the West End, a fine art show such as LAPADA in London, or even a part-time picture seller on ebay they believe the presence of a printed and signed CoA to be of great importance, and they are entirely wrong.
Unless it is signed by the artist themselves, their official agent or an internationally acknowledged expert on the artist a “certificate of authenticity” is meaningless. I would estimate that around 99% of all CoA’s in circulation are utterly redundant, and with respect to authenticity carry about as much weight as a note from the seller’s mum.

Here’s the truth; a formal Certificate of Authenticity is not necessarily required to prove a work of art is genuine. Any valid receipt, bill of sale or proof of purchase either directly from the artist or from a professional dealer will do – and is infinitely more useful than a so-called ‘certificate’ issued by someone whose signature carries no legal authority.
The CoA has probably become so important in buyer’s minds because many of us grow up with an innate respect for official-looking signed documents, but there are no legal parameters as to who can sign and issue CoA’s. Literally anyone can write a CoA, whether they’re qualified to or not. And these things have been issued for years so just because a CoA wasn’t issued yesterday doesn’t mean the work of art it purports to authenticate is genuine. When buying an old oil painting the maxim is the same as when buying any antique; the fact that something has age doesn’t always mean it’s any good, or even ‘right’.
In New York all auction houses and art galleries are obligated to certify the works they sell to be authentic which usually means providing certification based upon a consensus of experts in the specific field. In France meanwhile the close relatives or heirs of an artist are often designated as legal authenticators due to their knowledge of an artist’s work as well as academics with relevant degrees that have published in the field.
In my opinion, the most reliable methods of authenticating a painting are cast iron provenance and technical assessment. The provenance – or the documented ownership history – of a work typically includes auction, exhibition, or gallery labels, comparison with other similar works by the artist, testimony of past owners and agents, a CoA signed by a recognised expert, and any original sales receipts.

Where provenance is lacking, anyone looking to authenticate the attribution or age of a painting must look to science for assistance. A professional conservation report and/or technological assessment will help determine authenticity through detailed scientific analysis. For instance, the use of X-ray radiography and infrared reflectography which examine the original paint layers to determine whether the pigments are contemporaneous and consistent with those used by the artist in question. This method of course requires the owner to have both considerable patience and plenty of spare cash.