I
wrote something perhaps a bit too straight forward on this a few years back, but in the last year or so I'm seeing many more badges of the type that used to be considered "genuine". Use the picture of the "genuine" badge in the article as a reference.
A few weeks ago 7 were offered for sale as a lot at auction with the unusually low price of $500 for the lot (it sold for $550; usually each would sell for $250-400). I happened to visit and take a look before the auction and found some variations in design between them: most were curved, one was flat; many had light blue paint smudges on the edges. But no seam lines from die-casting. Nevertheless all were mint, and that also raises questions. They were being presented as genuine articles but I think the asking price indicates the degree of faith the sellers had in these items. And I've seen several more individual pieces in collections recently - too many too soon.
In any case, beware of these. If you can resist buying them when they're for sale, take the time to research the piece and also the seller. I'll try to accumulate some materials to add information to the original article.