This image looks very stock-like. Its sharp, clean and well lit and exposed, the guy in the background is in just the right depth of field spot - not so much that he distracts from the foreground subject and not so blurred that we cannot tell what it is. Very well executed and really adds to the image.
With the references 'petro' and 'crude' I'm guessing this is some partially distilled samples of oil and this explains the fairly narrow choice of colours from the rainbow - indeed you have made a good selection with what you have. I'd have scored this higher if it was a bit more 'out of the box' but as it is I give this an 8.