Hiya. Well I have to tell you that this could be accomplished in a variety of ways and due to the way most people think, it seems that you've left out some important pieces of the trick that are necessary to figure out what trick it is. Now this isn't your fault, there are actually many tricks that rely on the fact that people forget parts of them (Double Cross, the Cross Cut Force, etc.) So it's hard to help you here. I'd wait for some of the more experienced coin magicians to respond as they might be able to point you in the right direction.