Certificates of Authenticity, Insurance and Conceptual Art

Since Conceptual art is all about the idea being expressed via language rather than a physical form, what exactly happens when the certificate of authenticity is lost?

Here’s an interesting article on just this question, from a legal perspective. Pushing the question further from an art historical perspective, the question becomes, what exactly constitutes the work of art, the physical manifestation or the certificate? For those interested in the relationship between the market, law and art, this is a question quite worthy of consideration.