Oh Commodification... how I think I understand you, maybe?

Alright, so it's no secret that I have clearly had difficulty grasping commodification.  I read this Marxist section (and re-read it, and looked it up) and now I think I have it.  So I'm writing this to work out the kinks for myself, but I'm also writing this for confirmation from you all to see if I'm actually correct in this assertion.  So, I thought I would work this out first by saying that according to Mars, commidification happens in three parts.  The first is recognizing that the object in question is a function of the human organism, that it is is physiologically altered by a human.  The second is that the quantitative determination of value is the quantity of labor that goes into an altered object.  The last is that labor assumes a social form because social value is ascribed to the product and that value is based on exhangability.  So I thought the best way to describe this is bringing it back to the conversation we had about a month ago regarding a piece of artwork that Dr. Karl called a pure commodity.  The artwork is a function of the human organism because it is altered physiologically by a human.  The artwork is then given a value due to the amount of labor time exerted during the production of that piece of art, however it is also given its value because of the social relationship of the producers to other producers.  So, this is where I became a bit confused.  If a commodity is given its value based on other producers that are presumably producing similar products (or products that are ascribed the same labor value) then how can  a piece of artwork ever really have a value?  Because wouldn't that labor value (quantity of labor) be based on amount of time it takes to produce the work, as opposed to social connotations of the artist's work?  Although, if the artwork gains commodification (or value) status based on the third part (social value- value based on other producers), then the social status of a producer should be taken into account with the value attached to the object.  So then a piece of art is not an object of utility (such as the queen Anne chair that we talked about in conjunction with artwork), but has virtually no utility, making it an object produced for the purposes of being a commodity.  Which is how, I believe, a piece of art can be described as a pure commodity.  So now here's my question, is this right?  Is this what everyone else got out of the Marx reading?