Art History: what is real?

There is an interesting piece in today's Guardian blog about the judgement, by the "experts" of the art world, that a previously unknown painting is thought now to be a genuine but previously unknown Velazquez.  This link will take you to the Guardian blog item.  And this to the original Guardian article.

The newly-discovered painting by Spanish artist Diego Rodriguez de Silva y Velazquez at Bonhams auction house in London, England. Photograph: Bonhams


Jonathan James, in his blog piece, talks about the extent to which ordinary art watchers have any, or sufficient, knowledge to engage in the debate - comparing it to the general wealth of opinion, held by lots of different kinds of people, about, say, Shakespeare.

But I think theres' another question here, too - that this painting is suddenly valued at over #3m, just because it can now be ascribed to Velzquez.  yesterday or lat year it was worth a fraction of that amount, and now it is worth a fortune.  But it is the same painting.   The "experts" can have a huge influence on art  prices, and markets, but it doesn't seem to me to change the quality of the painting itself.  if we liked it before, we should like it no more just because of it's authorship.  Or should we?