As a novice, i don't really know what to suggest. But here i go anyway. ;o) One possibility is to take the texture into an editor, change it to greyscale and see if you can tone down the random bumps and bring out the grain more. I don't know how to accomplish that, but it's something i might play around with to see if it helps. Increasing the reflection might interfere too much with all the lovely refractions and reflections already happening in the image. You could try using a different material for the bump - like, use the Blue Bump texture, crank up the frequency and turn the bump value way down - that would help make it look like the normal variations in most surfaces. That's all i can think of at the moment. Perhaps someone else has the perfect solution on the tip of their cerebrum.