These badges were made by the finest enamel craftsmen in the world and they should look like it. The face should feel smooth to the touch, not a bit rough. All letters and the outline of the swastika should be in silver. Many fakes have them in gold. The oak leaves should always be smooth and taper off the edge of the badge.
Many fakes have a ridge or line down the middle of the oak leaves.
There should never be a raised edge or lip. Most fakes are cast, while the originals were die struck. Look at the badge under a 10 power glass to see if there are any scratches that would indicate finishing from a power tool to remove the above faults. Usually the fakes are thicker than the originals. Remember, it is very rare to find one of these awards in pristine condition.