[BigCliff]

A fine question! I agree with your premise that there is basically no way to be sure that the fly you have tied is a new one. Chances are, someone, somewhere has in fact put together the same combination of materials in basically the same way at some time. Whether or not they named it is another issue, and whether or not they made it popular via local word of mouth or commercial production is yet another. I suppose the best chance you have, mathematically speaking, of creating a never before tied fly, it to incorporate as many new materials as possible and as many parts as possible, thus making it less likely that such a combination has ever been created before. (some traditionalists have likely just groaned out loud) I reccomend incorporating royal blue and pink materials into flies, along with rubber legs, because all those are less common and work well to attract fish.