Nice clear shot. I think the central composition works well. Perhaps the style could have been pushed even further by cropping it as a square and using a highly polished coin with even lighting and adding a border to the image.
forgive me for being dense, but i'm not sure how this meets the challenge. it seems to be more of a macro/closeup than a miniature. oh well. the lighting is a little over-whelming.
What you've got going for you in this photo: good focus, detail, and lighting. What you've got going against you in this photo: uninteresting subject and off-center composition. Also, what you've done here is make something miniature look bigger while the goal for this challenge was to make something large look smaller.