I hate to tell you this Steve, but that's one of those colors that is heavily effected by the color of your light. As a graphic designer it was demonstrated to us in a seminar when we were asked to identify a color very similar to this under room light, then look at it again outside and see the color difference. What you've done looks pretty good, but if you really want to count rivets, mix it under the kind of light you expect it to be viewed under the most.