I've found several of these searching bulk wheats over the years. Aside from weight and magnetic pull, you can usually tell by the luster. Plated coins won't exhibit the "cartwheel" effect when spun under a single light source. They are very bright but have no luster. You can also usually tell by checking the edges of the devices. The plating will appear thicker and even look crusty or 'pushed up" around the edges of the devices and the rim itself.